FWIW, I would be cautious about treating this as a new business for the 3 year auto enroll exemption.
Even if a new LLC was formed, if it is the same location, same employees, and the same day to day operations, it may look more like a continuation of the old business rather than a brand new startup.
It may also matter how the deal was structured, such as a stock or asset purchase, and whether any controlled group rules apply.