UP students can do both: they can study when it is time to study, but also join protests when they choose to. It’s just a matter of time management.
UP admission is as fair as other schools out there. If you passed the UPCAT, then you can get into UP. There are other ways to get in, but it still requires that you prove that you have the skill to be able to get in (like talent tests for the arts). Money doesn’t get you in.
I would know because I had a relative who was an official in UP that got asked a lot by personalities to get their child in UP, but couldn’t because they lack the skill or intellect needed to get into the system.