If the abuse is egregious, you have a decent chance of pro bono representation or a lawsuit payout. In any case, activism comes with personal risk, and part of activism is accepting that risk while attempting to protect others. (This person was an activist, and it’s likely that they wanted to confine the damage to themselves.)

For the second part, having an empty phone is not a crime, and being arrested for this would be a major scandal. The tech press and political outlets would be all over it. It’s generally a good idea to avoid directly antagonizing border guards, though.