I haven'y had time to read any other replies, so sorry if I over-lap, but my thoughts are:-
-potty training, maybe she's so laid back she's horizontal, or maybe plain lazy. I had no intention of doing anything with my 1st. I had offered him a couple of times to go to the potty but he wasn't interested, so I did nothing, then one day he told me he wanted to use the potty and that was that. Maybe she's also just waiting to be told by her ds?
-my neighbour has 3 kids, 7, nearly 5 & 3. I nearly died when I was round her house & saw that the nearly 5 year old is still in a cot. I didn't go in the room, nor did I have a tape measure with me, but I'm sure it's just a normal cot too, not even a cot bed. I thought that was really wierd. I moved both of mine quite early to a normal single so find even a 2.5 year old in a cot a bit odd.
-I know a lot of people advocate quiet time for the kid in their room even when they no longer nap. It does seem a bit extreme that it's for 2 hours in the dark (to say the least) but surely, if he really objected he wouldn't do it? I mean when my 2 came to the end of their naps around age 2, both got more & moe difficult to put down - crying & generally objecting. Is she putting him down & letting him scream for 2 hours? If so, then I definitely think a cheerful "I think he's trying to tell you somenthing/he's at the end of his daytime rest' sort of comment. If he lies in the dark for 2 hours without a murmur, then he's either happy to do it or he's the most (worryingly) compliant child in the world, but you haven't suggested in the rest of your post that he's not a happy normal boy.
The cot, sleeping bag & toilet training I wouldn't mention unless she does. The nap, I might just ask in a genuinely curious way if he's ok with it, say by comparing with your ds's naps & when/how they ended etc