I believe all aloe flowers are all protandrous

But being protandrous doesn’t necessarily mean they are self pollinating.

Well if flowers are protandrous then it is mechanically very hard or impossible to self. I also read that if selfing does occur it decreases fecundity which further inhibits it from occurring regularly. It would be akin to an accident selfing occurs, not something some species do differently. Although I am sure there is one exception, there always is :p