Shorrick
You are confusing some concepts of validity and currency which are a bit confusing. I hope I use the right terminology....
In order to get a 61.75 certificate, the underlying pilot licence does need to be "valid" in the sense of "not expired" or "not withdrawn/cancelled/suspended" by the authority. On this basis you may indeed be issued an FAA pilot certificate. But now, as the holder of a valid FAA pilot certificate, you may not act as PIC unless you comply with the Part 61.56 requirements for a Flight Review. A "flight review" conducted by a non-FAA instructor or examiner does not count towards this. Conversely, the currency of your experience/ratings on the underlying licence is irrelevant. Your class ratings may lapse but as long as your licence hasn't expired, you may exercise your FAA privileges if you meet the FAA currency/flight review requirements.
brgds
421C