Injuries in baseball do happen and you can't expect the entire lineup 1 through 9 to be healthy 100% time. The Jays lack of depth this season on the roster really hurt when guys were on the IL. Jansen missed significant time, and other guys like Teo, Gurriel and Springer have missed some time as well. Also, maybe one of Gurriel or Jansen are moved for an arm. Benintendi is also a LHB which is what the Blue Jays need. Like I said he isn't a perfect fit, but would be a nice fit if he can be acquired at a reasonable cost.
Regardless, it's a moot point at the moment since it's very unlikely the Blue Jays could trade for Benintendi anyways unless certain policies change.