You are lying to yourself on this one. No one accepts a 20% pay decrease happily. Bonus or not, the active condition is one that vet players like Fitzpatrick, BRadford, and McCown expect to hit.
No one's saying he's happily accepting it, but indicating that he's somehow going to go flaccid the rest of the year and become a distraction is folly. Bradford knew the details of the contract he signed, and with or without the active bonuses, he's going to get paid lucratively.
Additionally, you can make the argument that Glennon should be QB2 either way based on Bradford's poor performance, and you're not going to activate all three.