they could in theory want to look at the backup, though let's be real, he's a career backup on multiple teams with as many INT as TD. meh. don't buy it. more likely they want to avoid a scenario where wilson plays last game, gets hurt, they have to carry him on IR for rehab, during rehab he vests more guaranteed years. they won't let you cut players who are hurt, worker's comp stuff.
either that or signalling his departure, or simply seeing how the team responds in his absence. if player x is a locker room cancer sometimes the team responds to him being benched. you then confidently cut them end of season.
the backup didn't completely suck starting the other day but you have to wait for the franchise guy and teams who fall for fools gold backup performances tend to stay lousy. so i think it's more anti-wilson than pro-backup.