In theory this is quite true. With the turbo probably not spooling until 3k RPMs in first gear, you would see the S/C boost from a dig with the turbo boost building as the RPMs increase. Since the turbo builds boost on a mostly linear plane as the RPMs increase, I would bet that he would only realize roughly a 18 or 19psi boost average across all RPMS, but then would be able to spike 28psi once the turbo is fully spooled.

The only other major issue I can see is the ECU throwing some major overboost codes once you hit about about 22-23 psi combined between the two...Though I'm not completely sure if codes would happen since only 14psi would be pushed from the S/C and thus the crank and the other 14psi would be pushed by the turbo, spooled up from the exhuast gases.