They really wouldn't. But the thing is, if the school doesn't make sense to the SEC to take, it's not going to make
Sense for the B1G to take.
Only a handful of existing ACC schools that you could maybe make the math work out for: UNC, UVA absolutely. Clemson and Florida State seems like it. Maybe VT or NCSU and maaaaaybe Duke.
It's really only 4-6 schools. Maybe 2-4. If they come into play, you better believe both the SEC and the Big ten are going to make a pitch for all of them. And all things being equal, I think most of them prefer the SEC. Carolina and Virginia might be the two who would rather look north because where there is a distinction between the two conferences is in the classroom (I know, cue the "UNC academics" jokes. But in all seriousness, they are a very strong academic institution).