The argument here is not the PA should be let off scot free. The argument is that proscribing them as an organisation is a massive and authoritarian overreaction to their actions.
It misleadingly describes the scale, coordination, and intent. It uses a minor detail to trivialize an act explicitly intended to reduce military capacity.
If we as a country are so at risk from paint chucking that we're resorting to proscription as our tool of defence, then we have some serious issues.