Yes to split the categories.
This past week I've been thinking about this decision more in terms of it being one of creating a new category to run instead of just splitting the categories. Wuggah's incredible 24:00 is still the undisputed Any% record, but this is simply the creation of an Any% NME/Grounded/No Abduct category that can be run without the use of Garuda. I'm reminded of the First@ categories and the split in NG+ and I think those divisions have largely been successful in giving people goals to accomplish and this idea of an Any% split seems in tune with that. I was originally in favor of merging the categories back together because Garuda was not needed to compete (or even the best strategy to do so) and it seemed unnecessary to have a split with how much better our strategies had improved, but I was mistaken. Now to compete with the Any% record you would almost surely need to devise a grinding strategy for a Garuda (a familiar that drastically alters the playstyle of the run). If a skip or some other technique was developed (like perhaps a way was found to use a hatched Balloon to fly you to 40) we would split the category without a doubt because the game is so different.
If the categories are split I would also push for a renaming of Any%/Any% NME and NG+/NG+ NME to something simpler such as Any%/Any% No Abduct/Fly and NG+/NG+ No Abduct/Fly. I've seen people before be confused about what the No Major Exploits refers to, especially since in those categories we allow things such as duping or glitched entry.