Those are all fair points. We really just don't know enough to make any concrete conclusions. Sporadic bursts of maximum intensity, high stress pitching will create their own set of unique injury problems in my opinion.
The Jays have their own information and might know the answers, but I wouldn't let my ignorance stand in the way of making Osuna a starter if I had to make the decision. For the record, I probably wouldn't do it anyways, but it's nice to have options.