A fed bear is a dead bear. If the mom can't be rehabed, they gotta put her down. It's too dangerous to leave them alive - even if you relocate, they'll just move until they find easy to raid people and become a danger. Black bears usually are fearful or wary of humans - if they lose this, they're a danger to people and themselves (people often defend themselves against bears with guns that fail to immediately kill the bear. The end result is a bear that dies a slow and agonizing death.
Surprised they're even trying rehab. It usually fails.
The cubs aren't as lost a cause.
Soldier's a ton of fun. Everyone craps on it because it's really plain in ME1, but in ME2 and ME3, they REALLY overhauled the character. In ME2, adrenaline rush is just broken, especially with stuff like the Revenant. (oh, and you get the Revenant on your first playthrough.)
ME3 is ridiculous though. You get all the ammo powers, and you can chain ammo power explosions for everything but warp ammo with concussive shot. It's kind of cheaty though, because if you take yourself, Garrus, and Ashley and equip everyone with Typhoon V-X, everything dies in seconds.