Yes, but she seems to believe that her son has done no wrong as he can use his free speech and is a beacon of courage and truth.
Free speech is protected, hate speech is not. Any communication which is threatening or abusive, and is intended to harass, alarm, or distress someone is forbidden. The penalties for hate speech include fines, imprisonment, or both.
In my book, having a sign which is offensive to trans people at an LGBT pride parade comes under hate speech because it was clearly done to upset the trans people who where there, knowing they would be there because it is LGBT pride. So yes, someone committing the crime of hate speech does belong in a police station and not being praised for harassing people or shown kindness for being so unpleasant in public.
And yes, before you bring up the kill a TERF signs, those people belong in prison too. Hate speech from anyone, about anyone, is unacceptable in a civilised society.