I think it is best to summarize possible avenues for Flight Review alternatives here and what has been proposed so far. These should be further questioned through local DPEs and FSDOs, in my opinion. Of course, the questions could also be posed for legal interpretations by the FAA lawyers.

The scenario is that a Sport, Private, Commercial, or ATP pilot certificate holder is out of Flight Review currency in a Category other than Glider. A Recreational certificate does not include a Glider Category. The pilot is not rated in a Glider. He can not or will not complete a Flight Review in an aircraft for which he is rated. Thus he can not act as PIC, and fly solo or with passengers, in a Glider, because at a minimum he is not Flight Review current.

Two alternatives discussed so far:

(1) Complete a Phase of the Wings Program in the Glider. It seems you do not need to be rated in a Glider to do this path. You could then at least solo in the Glider and continue training for the add-on.

(2) Complete a Sport Pilot Proficiency Check for the Sport Pilot Glider add on. It seems there is no hourly training or solo requirements to do this path. Then perform a Flight Review in the Glider since you are now rated in the Glider. You could then start down the training path (ie solo glider flights and additional training) to upgrade your Glider rating to the higher level pilot certificate if you have one.

On the other hand, the above assumptions may not pan out and I am not as experienced as Bill to claim with certainty otherwise. And, the proposed alternatives may involve more time and expense than doing the Flight Review in the first place, as Bill has mentioned.

So again, we should get confirmation from the local DPEs, FSDOs and FAA legal interpretations before starting down the path of any alternatives.