The Nazis under Gleischschaltung banned any organisation that wasn't closely allied with their principles and organisation; it was almost a matter of principle.

That said, German Studentenverbindungen had played a big role in politics ever since the early 19th century, and tended to be quite reactionary (pro-Prussia, even pro-monarchy). Like all other reactionaries at the time, they initially supported Hitler for his nationalism (with a few reservations), but the Nazis always knew that the reactionaries were more in favour of the Second Reich than the third Reich, so they too got disbanded after the Nazis were strong enough that didn't they need them any-more.