Not entirely sure Bayern Munich will give Manchester United an easy victory, because even though Bayern Munich has qualified for the round of 16 but I am sure. Of course Bayern Munich will still play their key players, although maybe not completely but at least Bayern Munich will also try not to be defeated by Manchester Untied. Because yes, of course Bayern Munich also has prestige and thus, then Bayern Munich will not play elephant football to let Manchester United win easily, I am sure that will not happen.
This will of course be a very tough match for Manchester United, even though they have very little chance of qualifying for the next phase, of course Copenhagen and Galatasaray will go all out in this group phase match. Of course, the two coaches will find out how to mix their ingredients to win the match. If the result is a draw and Manchester United can win against Bayern Munich, of course you will qualify for the next phase. It is true what you said that Bayern Munich will rest several of its players, to avoid injury problems to its core players, as they have already qualified for the next phase. Even though they are playing at Mu home ground, Bayern will put up various resistance in the match.