Depends what boost it does it at..mine does it at 7psi or less, I have the BOV spring pretty tight to avoid leaking at idle and stalling, If it does it at high boost it can be a problem as it strains the shaft with the sudden stopping of the blades.
This car is only running 6psi so it is fine..when you want to run more a BOV would be wise, that said Dave ran no BOVs on his T04Z at 20psi and it is fine, apparently BB turbos are more resistant