His rhetoric is a double edged sword.
He's going for an "all or nothing" approach, when the people are now closer to accepting "all" rather than being willing to continue suffering "nothing".
It isn't my rhetoric though. I'm not the one toppling statues of Grant and Francis Scott Key for having owned slaves.
When the argument is "Don't take down General Lee, or else you'll soon have to take down Jefferson and Washington" -- then the point also being made is simultaneously the opposite: "Dude, we're absolutely 100% certain we should take down General Lee, so what you're doing is actually convincing us that we should take down those other people as well."
That's the danger with slippery slope arguments: once you make the slippery slope argument, you can't then say "Nope it turns out those situations are vastly different after all, and there's no need to cancel Jefferson just because you're cancelling Lee"
See, this is where things get slippery. There is evidence to suggest Lee was "overly harsh" with his slaves, but he also was coming at runing his plantation after a career in the US Army, where mind you,
flogging was legal for use as a disciplinary option for
troops and sailors until January 1861. As such, it is extremely likely you'd find records of Lee either having ordered, or been within "one or two removes" from
whites who had been flogged. In that context, he's not going to be very hesitant about using harsh measures against slaves if he'd also do it a white guy.
There were some other things he did with his family's slaves that were despicable, like failing to honor requests for slaves to be freed, breaking up said families when they objected to not being immediately freed(because the estate was deeply in the red), and other !^@& like that. What become relevant here is that 1) He was not an eager defector to the confederacy, he only sided with them because Virginia did. 2) The war ended for him when he surrendered, from what I'm aware of, from that point on he worked to help heal the wounds caused by the war. He didn't live for very long after the war concluded, passing in 1871 IIRC, but he was trying to make amends by all accounts. Even in the face of being very personally slighted by the Union in the form of his family estate in Arlington being turned into a cemetery for Union Soldiers, among other things. He had reasons to carry a grudge, but he made the effort to move on.
Which then becomes a challenge with General Lee and his positive achievements, and he had several. And trying to decipher to which thing a particular statue of him may have been commissioned. Not every statue of Lee is necessarily bad, a small number of them are probably quite
good in their intentions, although there probably are a great number of them with more dubious intentions behind them.
But right now, all the narrative is at present is "He fought for the Confederacy, he's evil, tear it down."
Most of the other Confederate Generals may be entirely different stories, I'm sure a few of them never truly stopped fighting the war, and have at them. But the criteria people are using to pass judgement on the memorials and statues is extremely binary and black or white in their choice matrices which is really weird for the a social movement which seems to want to be all about those "shades of grey" on just about every other subject under the sun.
It's rank hypocrisy on one front, and alarming in other ways. They'll cry about how people in modern society should be excused their serious crimes because "it's society's fault" they turned out that way, but when dealing with historical figures
in their historical context they can't be bothered to look at what "society's role" was in their decisions at the time.
If you don't want those other slave-owners also cancelled, you should be instead focusing on saying that a statue made to honor an evil cause is different than a statue meant to honor a person's positive achievements, regardless of the evil actions in that person's life. e.g. Perhaps Einstein was a bad husband and father -- but a statue to Einstein would be for his achievements as a physicist, not for his family life. Similarly a statue to Jefferson would be for things like his Declaration of Independence, not his slave-owning.
Most statues to Jefferson are for the Declaration of Independence and his other other roles, including PotUS, he fulfilled during the early days of the country. Same thing for George Washington, he's honored as the General of the Continental Army during the Civil War, and for being the first President of the United States. Their slave ownership isn't even on the proverbial RADAR for most people, and in some respects, that is a mistake as well, as it is another form of "erasing history" as people would rather not think about that particular fact. But this binary decision tree BS needs to stop, and anyone who is excusing people who are pursuing it really need to look at the person in their mirror very long and very hard.