did you heat it up enough? when your heating it you heat the aluminum actually changes color the surface gets a haze, don't heat it up beyond 1100F.+ because you will cause the alum. to melt, but if you concentrate on the bolt it will come out just have to be ready have a good hex driver T-Handle prefered and once you see the bolt turn a slight bit red grab that driver make sure its in there properly and give it a good turn you should actually see a puff of smoke from the lock tight being burnt.
now unless you stripped the bolt already have you ?
then you will just have to get a new holder and cut that old one away or melt it,