Young went down following a tackle by Kagisho Dikgacoi during the first-half of the 2-0 win but TV replays showed the United wide-man had initiated the contact.
Referee Jon Moss was not fooled and promptly cautioned Young, although he later awarded a penalty when the same pair tangled again, even though some observers felt the latter incident warranted another caution.
The first was far more clear cut though and left Moyes feeling less than comfortable.
"I don't want my players diving," said Moyes.
"I don't want anybody doing it.
"The boy (Dikgacoi) definitely throws his leg out but I think Ashley has put his leg into his leg. It is not what I want."
Young has previously been in trouble for diving, although it was difficult to argue either way for the second offence, which triggered a penalty that allowed Robin van Persie to open the scoring and led to Dikgacoi's dismissal.
"I don't like the rule where every time it is the last man it means it is (a red card)," said Moyes.
"I thought it was harsh.
"If I was Ian Holloway I would be disappointed.
"OK, it might be a penalty. But I don't think the boy made a challenge to wipe him out.
"Unfortunately that is the rule."
United did not impose themselves in the manner Palace boss Ian Holloway feared and it took a late free-kick from Wayne Rooney to seal the points.
Rooney was only a confirmed starter on Friday evening after he had tried out a strange looking cushioned head guard to protect the area where he had 10 stitches following a training ground collision with Phil Jones.
"It was a difficult decision," said Moyes.
"We got the headband on Friday and we wanted to see how he felt with it. If I thought he could wear it I would try and get him out.
"He tired a little bit in the second-half but I wanted to get the 90 minutes out of him because he lacks match practice.
"It helped him towards the overall goal of getting him match sharp."
Moyes was also able to introduce £27.5million new-boy Marouane Fellaini for his debut, although the Belgian was overshadowed by fellow countryman Adnan Januzaj.
The 18-year-old unsettled the Palace defence more than any other United player and won the free-kick from which Rooney scored his first goal since March.
"I considered playing him from the start," said Moyes.
"His performance when he came on showed it would have been merited.
"He didn't looked fazed and did a lot of good things.
"He moved the ball well. He is going to be a good player."
After being hit by a two-match touchline ban and £18,000 fine following his comments after a controversial defeat to Tottenham on the opening day of the season, Holloway opted to keep his temper in check this afternoon.
His initial reaction to being asked about Young's conduct was to turn his back and declare: "I think that is safer don't you?"
Holloway then turned round and offered a more rounded assessment.
"My opinion doesn't count," he said. "I realise that now.
"All I can talk about is what led to it, which is us playing the occasion rather than the game.
"I will not get drawn into a situation where people have to make decisions and they affect me. Emotionally I am in the right place now.
"I would like to keep my money in the bank and pay for my own daughter's wedding this summer.
"I don't talk about other people's players. If you want to meet me down the pub later on I will tell you exactly what I think."
@brightandedgy - spot on. It is rare. Maybe Moyes speaking out might encourage other managers to do the same. We shall see.- big dave