I once had this said to me by my SIL who hinted that letting my ds play constantly with Tom The Tank would cuase problems as he grew up out the age appropriate for such things!
I was unable to argue my point- and was only later that i thought how her son loves football and is always playing/talking/watching etc football.
and noone bats an eyelid.
yet 'our' children obsess in a 'different' way and it gets commented on.
So, for me....I have long since accepted that my boys obsessions are part of them- and to take it away would be like removing part of them.
however...I am diagnosed with Obsessive Compulsive Disorder....so am a bit biased!!!
what i have learnt regarding my OCD is that the important thing about ANY behaviour...appropriate,inappropriate, obessive or different...is whether it is safe- and secondly does it have a negative impact on self or others.
This is a good way to look at an autistic persons obbsessions....if what they 'need' to do hurts them or others...then we'd 'obviously' have to stop them.
Also.... FlyMeToTheMoon ..... do you feel that you are 'controlled' by his obsessions??? at times i feel very controlled by them! I find i am actively alert and looking at all times for something that will interest my boys...i often feel that I feed their habit!!!! mostly i get it right....but once when ds2 was about 8 and was obsessive about pokemon... i was chuffed to bits to find him a pokemon wallet. He threw it across the room and told me that 'just cos i like pokemon, it doesn't mean i like pokemon wallets'
so.... to summarise....ignore your friend!
your son is only 3- i never thought ds2 would ever stop requesting that i call him percy or Gordon Train at the top of my voice....and imagined him only ever playing with trains...however he has moved on...i find with my boys that they do now transfer from one interest to another- and the worst times at home are when they are 'in between' and they are therefore out of their comfort zone.