While enacting a substantial change does not appear possible you can protest and people do, at least in larger cities streets become full with people holding banners. (Photo galleries were posted on HN and FWIW I have supporting information from someone who is directly there.) Protesters are selectively detained, but there is no mass murder or vanishing of people unlike what I imagine would happen in China (or Hong Kong now) so not sure if 'totalitarian prison' is entirely descriptive.

Blocking is a trade-off. Take Google access as another instance. On one hand, it lets sane people not be limited to just state propaganda by watching live the destruction their government is enacting, as well as communicate to the outside world that they do not support it by protesting and sharing photos of protests. OTOH, it lets bots mass-report YT livestream watchers, causing automated ban waves. If we block access, we address the latter, but also eliminate the former.

There are ways to protest without risking arrest: walkouts and silent vigils. Nobody will arrest people simply walking on the streets in silence.

Imagine the power of rivers of people covering the Russian city streets at the same time, simply walking in silence. No signs, no screaming, no pushing against police - just walking. It would send a strong signal to the leadership with minimal danger to the protesters.

Just like Ukranians are being murdered.