It’s load management disguised as “injury maintenance/left knee soreness.”
Correct decision to sit him, though. He played 35 minutes last night and there’s really no need for him to play in any back-to-back games at all. This is why you went out and got Al Horford, who was given a rest and sat out the Cleveland game. You now have bona fide backup big man options for a clustered schedule. Horford, Kyle O’Quinn, and Norvel Pelle is enough center depth to get a November road win in Orlando.
Seems like the oddsmakers got an early sniff of the Embiid situation, because the lines shifted significantly about six hours prior to public confirmation. That’s not news in itself, since lines move all the time based on a range of information, but it does seem that the books were on to this even though there hadn’t been a report about Embiid’s status.