The 20-year-old missed two months of the season due to a bad bout of glandular fever, and has not started a game since December.
The attacking midfielder has been eased back into first-team duties as a substitute this month, as United chase a top-six finish.
But Blades manager Wilder is adamant Brooks – who was yesterday called up to play for Wales Under-21s – is not fit enough to play 90 minutes.
“There’s no conspiracy theory,” insisted Wilder, about a player linked with a big-money move to the Premier League this summer. “He’s not fit enough for 90 minutes yet, that’s not really what the medical people want.
“So he can start or we can use him as an impact player later on in the game. I think the world of him, the players think the world of him and the fans do too.
“David makes us better, of course he does. But we have to be sensible given the situation. If we overload him and lose him, people are then looking at me asking ‘is he stupid?’ That’s if they’re not already.”
United sit two points behind sixth-placed Middlesbrough in the scramble for a top-six finish.
With nine games remaining – plus the possibility of an extra three play-off matches – United will need the attacking threat provided by Brooks, and 15-goal striker Leon Clarke.
The latter is struggling with a hamstring and, again, Wilder is reluctant to rush Clarke back, only for the player to suffer a setback.
Wilder said: “There’s nine (games) to go. That’s a fifth of the season roughly left. That makes it more awkward in terms of the decisions with Leon. He’ll be okay after the break, but it’s whether we take that chance.
“Brooksy could start but it’s still 55 or 60 minutes. We’ve got that option though. We can do it the other way, where he comes off the bench. Leon is obviously the bigger gamble but he’s only been out two weeks. He’ll have to come through tests.”