Its a bit “young” to need a wheel bearing, though its certainly possible. What, exactly, did the mechanic do to check the wheel bearing? There a lot more that can be done other than just guessing based on noise.
When the tires were rotated did any of them end up swapping sides? I.e. sometimes rotation just means swapping front w/ back, but no left/right swapping. Unless there is other clear evidence of a wheel bearing issue I am not inclined to cross off the tires.