De Gea came under fire after his punch allowed Clint Dempsey to snatch an injury-time equaliser for Tottenham at White Hart Lane last weekend, but United boss Sir Alex Ferguson kept faith with him for the FA Cup tie against Fulham.
And the 22-year-old enjoyed a comfortable evening at Old Trafford with the Cottagers failing to put any significant pressure on him as they went down 4-1.
"The criticism of De Gea has not just been over the top this week, it has been all season," Coton told MUTV.
"Whenever a goal goes in they seem to point the finger at David. I hoped he would play, just to shut the rumours up that he had been dropped."
Coton believes United should stick with De Gea because he does not see any worthwhile alternatives that could realistically be attracted to the club.
"Over the years we looked at a lot," he said. "We looked at Buffon but there was no way we could get him. He just didn't want to come out of Italy.
"We tried to get Edwin van der Sar a lot earlier than we did but it didn't happen.
"It is not a matter of 'it is Manchester United, we must be able to get them'. There are certain situations when you can't."