I don't buy that.
If that's the case, why doesn't apple just require that 4pin code that you made when setting up the fingerprint scanner if it register a 3 party scanner?
It would be easy to program. Kinda like,
If scanID != StoredScanID
FingerprintScannerEnable = false
(i am not a programmer, as you can properly see. But it should get the point across)
Besides there is easier ways to bypass that lock. Hackers releases and updates tools and guides all the time for it.