Hamate bone isn't super strong. The cutoff between a "bruise" and a fracture of the bone is pretty slight, but they likely wouldn't treat surgically unless there is a definite fracture line that a screw would truly help with. The bigger issue is if he has to alter his swing to deal with the pain and prevent future injury.
I hate facing side arm guys. I feel like if you ever had a side arm righty and a side arm lefty you could stash one in LF and pitch the other one so you are same handed and just destroy a team. This isn’t actually serious commentary other than the hate for sidearmers.