The high functioning ones who know and understand how to smoke probably could. This is a highly unusual question in that autistic people generally are supervised or cared for by others, and marijuana just wouldn’t be part of their lives or treatments unless prescribed by a doctor. They would also have to live in a state where medicinal marijuana is legal and they have been given a medical card to carry marijuana and use it as a medicine.
For recreational purposes this isn’t exactly a question one could ask of the high functioning autism population of adults. It would most likely get them into a lot of trouble, and trouble is something they understand that they don’t want to be a part of. Ergo, they would probably avoid the question. It’s also not a scientific study that has ever been performed, so there is no evidence to support or negate the use of marijuana amongst adults with autism at this time.
It might be a question of interest in other countries that have legalized marijuana, but in the United States it just doesn’t apply. Absolutely no research of any kind has been performed on this particular subject.