Granted there are some moves the SEC could/may make that would harm the ACC. However, the purpose of those moves would be to improve, financially and otherwise, the SEC. Any harm to the ACC would just be unintended consequences. IMO, the idea that the SEC is drooling to annex schools like VT, UNC, Duke or whatever the flavor of the week ...is just ridiculous.
Frankly, I see VT and UVA more likely to the BIG, than to the SEC. VT admin are working hard to get Tech up to AAU standards, although I am not sure AAU membership would be absolutely required for a move.