By themselves, sure you can write "I support HAMAS" but to then go advocate "Death to America" in support of HAMAS is maybe over the line? And beyond words, if you occupy public or private property (a school, a street) and disrupt others, is that legal or actionable? What if you indirectly or directly cause injury or damage, is that legal or actionable?
Words of support, okay, words calling for action, no, anything beyond words, no.