Part 1 (supporting genocide), yeah, sure. But part 2 (those who conduct it) is asking for trouble, especially given how vague "genocide" is. That would exclude basically every military or political leader of any halfway powerful nation. Hell, it would exclude the likes of von Braun. According to some, it would exclude anyone who thinks there are only two biological genders.
The UN definition of "genocide" is remarkably unhelpful:
In the present Convention, genocide means any of the following acts committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group, as such:
- Killing members of the group;
- Causing serious bodily or mental harm to members of the group;
- Deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part;
- Imposing measures intended to prevent births within the group;
- Forcibly transferring children of the group to another group.
By this definition, someone who kills *one* person commits genocide. Someone who attempts to deprogram one person in a cult can be considered to be committing genocide.
So... "Political Scumbag X supports genocide" is an uninformative statement and a bad basis for policy.
Is Putin bad? Why, yes he is. Is he *historically* bad? Yup. Should people be prevented from expressing support for their national leader? Nope. Beyond the ethics of it, it's kinda best to know where people stand sometimes.