You would only get criticised as a senior referee if keeping the cards away caused you problems, such as losing control. He dealt with the one nailed on caution for Maguire, which I think could easily have been red given the ball was in a different postcode at the time of the foul, but I don't think there were any mandatory cautions missed.
I personally thought Oliver was excellent and contributed to a very entertaining first half. He couldn't be blamed for the lessed entertainment in the second half, that appeared to be down to United sending out their under 15 team after the break