Whether he's worth holding or not depends on what is available on the FA wire for closers. As you said, the Jays are a decent team and I wouldn't drop him for a Mike DeJean or a Franklyn German, based just on potential save chances. If there are no other closers out there, you can't justify dropping him because you'd be giving a free saves source to one of your opponents.
I also don't think that he can possibly continue to be this bad. If you look at his career stats, after his first two seasons, which were back and forth between the minors, he has never posted an ERA greater than 4.00, and last year his WHIP was 0.99. Also, his current ERA is greatly inflated by these last two appearances at Great American. If you take those two disasters out, his ERA is under 4.00. I kind of think you have to hold onto him, but maybe bench him at least until the Jays dump his as their closer.