100%I'd question that assessment. The Carabao cup would not add that many games to the schedule that he couldn't achieve what you outlined. And it would give him a few extra games to keep the bench players sharp.
I think he picked the team he did because that B team had shown in preseason that it could play well together. And probably showed the same in training. So he felt he could start them and bring in first XI players as needed. In the end he wasn't that far off. The B team did get a result: a draw at an away PL ground. It's not like we got blown away.
There is no way he will ever "throw" a game for another. He'll take calculated risks with the bigger picture in mind for sure but he just wants to win, everything!