While building raid group- about 20 or so people in group- all with assist. Immediately after inviting a single person the entire group was disbanded... and not by the lead player... Is there a method out there allowing people to disband a group without being lead?!

There is a slash command somethig like /oq disband or /oq dump all that will disband the group.

It is not recommended to give everyone raid assist as some users will troll or mis user this function.

you only need assist to remove everyone from group using a simple macro. it's not an oQueue thing

dont give out assist and have everyone wait list. there's no reason ppl shouldn't wait list. usually they're either trying to skip around your requirements or get their friend in that is too lazy to install oQueue.