He's is correct. Because of the size of SAB and because they have that swirly water area where the water swirls you around they must have lifeguards.
The last week in August it stays open to 10:00. My kids always use the quiet pool at BC. It was never ever crowded especially late at night. I did have to warn them to make sure they keep their voices down because of the surrounding villas.
These were last August, when Epcot closed and we walked back to our villas