I think that is (mostly?) true... But what I heard was that they needed to use induction motor on one side so that it could "torque sleep" (freewheel without making power) for cruising efficiency.
Apparently the new type of synchronous motor is not able to "torque sleep". Unlike with P-AWD Model S & X, where the rear motor does most of the hard acceleration off the line, I think it ends up reversed in the Model 3, where front motor does the "heavy lifting" off the line, and the rear motor is used for cruising efficiency once you are up to speed, and then the front motor "goes to sleep" until you need hard acceleration again.
I am not sure if they ever intended to use the new ("gen 3" as you may call it) synchronous motors for both front and rear on AWD.