Lots of question marks on the roster right now. And vaccination status must be playing a role in how the team reacts. There are apparently several (unnamed) unvaccinated players who won't go to Canada anyway. The team knows whom they will be missing, but we (I) don't.
So, in Kepler's case, if he is not vaccinated he would miss three days there anyway and maybe they would go ahead and put him on the IL. If he is vaccinated but other outfielders are not, then they have to hope that he will be available in Canada since they will be short-handed already and maybe don't put him on the IL, playing shorthanded in Detroit in hopes of being less shorthanded in Toronto.