The OPs question is very valid, but it hinges on an assumption. The reason why women are obligated in daled Koisos is because they were also included in the miracle of Mitzrayim. This is also the reason given for women being obligated to hear the Megillah, even though its a time bound Mitzvah.
The question now becomes- is the obligation to drink ad d’lo yoda as a remembrance to the Neis Purim? Or perhaps, even though it was triggered by the Neis Purim, the Mitzvah itself isn’t merely one of remembrance rather it’s a “different beast” so to speak?
I think it could be argued that the actual obligation of Ad d’lo yoda doesn’t really have anything to do with the actual Neis itself. It isn’t a zechira in the classic sense, which would carry the dictum of “af heim hayu b’oiso haneis”. Rather it’s merely a Mitzvah to attempt to see the unseeable, in a day where we’re pressured to peer beyond the veil of physicality to perceive a deeper reality.
If that’s true, then the Mitzvah would carry the same laws of “zman grama” and women wouldn’t be obligated.