It depends on what kind of search it was? Auto search, terry frisk, house search, car search? Was it in the course of an arrest or questioning? What was the cops reason for stopping him?
If a cop has reason to question anybody, and he fears for his safety, he has the right to do a stop and frisk without having any probable cause. It's a lower standard. If he feels anything that could be drugs or a weapon, he has a right to search further. If he doesn't feel a weapon or drugs, he'd need probable cause to search any further. But a cop can make up any bullshit reason for probable cause. The initial search can be a frisk in the course of an arrest or questioning. If his reason for questioning him is because his head is shaved, that's probably not enough. If he's questioning because his head is shaved and he's wearing gang colors in a gang area, that's on the border.
If he's stopping him because his head is shaved and he looks like somebody who's out on the wire, and he wants to question him just to see if he has the right identity, he has the right to pat him down prior to questioning just to make sure that the cop isn't in danger. If he does find something incidental to the pat-down, then it's totally admissible in court.
If the dude fights it, and wins, and finds its a violation if his 4th amendment, then everything found during the search would be inadmissible.