Tbh I don?t think this is quite as black and white as yanbu/yabu, although I can see why it could be seen that way.
Firstly, obviously if your ds? disabilities are such that he has no sense of danger at all and has severe anxieties then any desire to do things more independently need to be assessed probably on a case by case basis. Having said that, he is twelve, and unless his disabilities are such that he will never lead an independent life and can never be left unsupervised then there is going to come a point when he is going to want the freedom to do some more ?normal? things iyswim, and there does have to come a point where this is facilitated. Unfortunately that sometimes means getting it wrong before you get it right iyswim, and I?m not sure camping in the back garden would have been my starting point on that one either, but assuming he will one day lead an (as much as possible) independent life, at some point there does need to be some facilitation of gaining some independence in the same way any of his peers would iyswim. Now I?m assuming from your descriptions that although your ds has ASD, he doesn?t actually have learning difficulties per se, so at twelve he will certainly realise that his peers have independence that he has not yet been allowed, and therefore will seek this ? iyswim?
I think the posters who are saying that it is pure luck that nothing dreadful happened are sending out a truly horrible message ? that it should almost be expected that something terrible would happen and that it?s only by chance that it didn?t. Actually it?s not by chance at all. The child camped in the garden, he did so safely (in spite of fears that he has no understanding of safety) and nothing happened. That?s not chance ? that is credit to the child that he was responsible enough on this occasion to camp out in the garden alone and this IMO needs to be acknowledged. We need to stop living in a society that views disability as a worst case scenario rather than accepting that many people with disabilities do gain independence skills, and that although this may take longer in some cases than others,, we need to look at assessing risks rather than living in a fear-consumed culture that disallows independence on the basis that bad things happen through luck rather than anything else.
The reality is that ?bad? things are a rare occurrence. Sighting cases such as Madeleine McCann and the little girl taken from her garden are not comparative at all, but even if they were, the fact you are able to quote names of only a handful of cases which have happened over the time frame of several years speaks volumes as to just how rare these instances are.
Now, I can see why the incident in Spain may have made you more anxious, however, if you look at it from a different angle, your ds locked himself out, he didn?t wander off, he didn?t go anywhere else, he merely knocked on the door to be let back in, and although he became anxious and had to be taken to calm down, the fact is he didn?t behave irresponsibly on that occasion either or put himself in danger.
I can absolutely understand why you are anxious about this, however there?s a fine line between letting go and holding on, and so often it is difficult to know where that line is drawn, and sometimes we as parents get it wrong ? on both sides ? it is possible to over protect a disabled child just as much as it is possible to not consider their disability when risk assessing.
Lastly, I think there is a real possibility that you are projecting your own issues about this on to your ds. You say he said he only did it to make his dad proud, I wonder whether that?s actually the case or whether that?s what he thinks you want to hear. You have said to him that you?re cross with his dad ? IMO it is never acceptable to involve the child in the feelings between the parents ? he doesn?t need to know if you?re cross with his father, that is between the two of you and should remain such. You need to stop your feelings towards your ex on to your ds, because that isn?t going to be helpful either.