Murray allowed it to affect him but Federer was also in top form in those latter two sets, credit where it's due.
I agree Murray let the delay affect him, but would Federer have been in top form had the match continued without interruption? He doesn't have quite the same physical stamina he used to have. As it was he had a nice rest and a chat with his coach and came back out a different player. Andy on the other hand was lost.
Anyway Andy learnt a lot from that loss, and gained a lot of new supporters as well, so on that level it was a blessing in disguise.