Yeah I can totally understand what you mean. Unfortunately at the very business end of the season in our current state, we can't approach things from an injury prevention point of view. I know we'd be even more fecked if Bailly got injured, but one could've said that last Thursday about Rojo, too. That we shouldn't risk our two last CBs, so rest the other.
But we needed a win (or 0-0), so we went with more or less our best possible lineup (bar Herrera). When you really need to win, you have to accept the risks and go for it. Hope for the best and fear for the worst. Oh and Bailly could get injured in training anyway.