I agree up to a point and I said this a few days ago. Either he would play a strong side to give them more playing time together or he would rest as many as possible due to fixture congestion. Whichever was the more beneficial in his eyes.
Ultimately I think that the way we tired after about 60 minutes in our last game made up his mind. The players needed a rest more than time on the pitch together. I think he was probably pleasantly surprised how quickly we implemented a few of his tactical tweaks as well.
Theres honestly not much benefit to playing half a full strength side when you are as disjointed as United so it was always likely to be all or nothing.