DonaldD, to the extent that politicians routinely use bad events to prop up their own success, I agree with you there. It would obviously have been nicer to just offer his condolences to Floyd's family or something and leave it at that. However I will mention that the most immediate and preceding context of his speech prior to the comment about Floyd was that the police (and Secret Service, and National Guard) did a great job cleaning up the cities, which have restored to order. And right after that he goes into the bit about how Floyd would be proud. So if we were going to ascribe an 'implication' in the placement of invoking him, it would seem to be in context of the issue of law and order and establishing secure city spaces. I suppose in some oblique way "law and order" would have been better for someone wrongly killed by an unlawful police act, but on the other hand 'order' seems to typically reside on the saw of those enforcing order, i.e. the police. So a 'law and order' narrative seems to me mostly antagonistic to any kind of sympathy with what happened to Floyd.
It's also possible the speech isn't very well written around that part, because if you take the words about Floyd out of context they're actually nice enough, if we ignore the preceding paragraph about ending the looting.