20 years ago, when the alternative was open knee surgery - often worse than the injury itself - plenty of NBA players would play on mild meniscus tears, in many cases for years till the end of their careers. They'd have diminished range in some games, they had to ice their knees a lot, have them drained and take pain pills. It still happens.
No significant risk of overcompensating, as long as the pain is tolerable and he's moving decently. It's like playing with arthritis: if all the players suffering from it decided to sit down, teams would need 30 players rosters because at least 20 of them would always be injured. Pro athletes aren't supposed to be healthy, the human body wasn't designed to endure the level of physical effort they go through. If Roy can deal with the pain and the inflammations are under control he should play.