Having already won the Premier League, Sir Alex Ferguson could rest a number of big names for United's final game at Hull on Sunday in preparation for the Champions League final.
That could boost Hull's chances of beating relegation and infuriate the likes of Newcastle, Sunderland and Middlesbrough, who are also battling to beat the drop.
It is a scenario familiar to Warnock, who was in charge of the Blades side relegated two years ago after West Ham snatched a last-day victory against an under-strength United.
Warnock told BBC Radio Five Live: "What will they do? Fine them two bob? Slap their wrist?
"It just won't happen. It's just the luck of the draw. It's just how it happens, that's life.
"At the end of the day Newcastle still have to get a result at Villa and Sunderland have to get a result, possibly. They have to worry about themselves."
There has also been a suggestion the troubled north-east clubs could sue United if Hull overcome a weakened side to survive at their expense.
But Warnock added: "I can't see people suing Sir Alex and his club, it is just one of those things.
"I have every respect for him, I always have over the years - although I lost a little respect for him that day.
"But I am sure that doesn't bother him or anyone else."
Warnock admits the situation is probably unfair on the other clubs in the relegation picture but claims United's youngsters could still give Hull a run for their money.
Warnock, now manager of Crystal Palace, said: "It is disappointing when you do see they are not playing their top man but Sir Alex is single-minded and I don't think for one minute he will be concerned, when he picks his team, what happened to Neil Warnock or what happens to Alan Shearer or Phil Brown.
"I'm sure Hull will be absolutely 200 miles per hour on Sunday against the youngsters.
"They usually come into a team that is full of internationals and so it is easy for them to show.
"When the team is comprised 80-90 per cent of youngsters it is very difficult to shine against a team like Hull.
"They are not a bad team and wouldn't be in the Premier League otherwise. They are going to give everything in front of a packed house.
"But Manchester United's youngsters can always get a result against anybody on their day and the thing Hull haven't got is (Carlos) Tevez.
"He was a world-class player playing for West Ham that day and I don't think they would have beaten Manchester United that day if they hadn't had Tevez.
"There is still a great chance for the north-east clubs that Man Utd will go there and prove they can get a result against Hull."