It is. The Romani aren't vagrants and they're doing nothing illegal. Calling them vagrants is charged and misleading.
> Vagrants and transients are often dangerous and mentally ill.
That can be true. Again the Romani aren't vagrants and using the word to describe then implies a level of danger and/or mental health issues that isn't evidenced.
> It is reasonable to use state violence to suppress crimes.
No-one has asserted otherwise.
> the control of dangerous animals being similar to the control of dangerous people is not extreme.
It's generally accepted the dehumanising a people or culture is extreme, I'm not sure how you can argue otherwise. There are any number of alternative metaphors that could have been used (not to mention that the argument could have been built on its own weight) that wouldn't have involved comparing an entire people to a pest that needs to be controlled with lethal force.
Vagrants and transients are often dangerous and mentally ill.
It is reasonable to use state violence to suppress crimes.
Using a metaphor about the control of dangerous animals being similar to the control of dangerous people is not extreme.