Not trying to go against anyone here but are we sure that was the intent of this person and not their initials or maybe another explaination. ASD would be an acronym and not a slur if I am not mistaken and if it has to do with this maybe it is not for nefarious reasons maybe you should ask this person the meaning or just chat with them about it so that maybe it will clear things up for you. If they show it as mean spirited then yes by all means it needs to be fixed. Parents with children that have this condition tend to really embrace a "I wont let this win attitude" and it may just be a trivial way of showing respect in their own way peolple tend to do things that are questionable not knowing it may be seen in a negative way so talking with this person should help you in taking the next step.
Fair points for certain. The person was using autistic as part of the name in a clearly derogatory way. ASD, is the acronym I used in this post, however, not the player name in question.