Primary school asking parents to not change Nappies in the toilet

[Laushe]

My 5 year old is sen in a mainstream until he transitions to specialist in September. He's toilet trained at home but requires nappies at school/outdoors due to anxiety over using the toilet.
He goes into school 5 mins after gates close as he's an escape risk. This past week just as we've entered the gates he's done a poop, so I've taken him into the reception "accessible" toilet, changed him, bagged the waste and placed it into the bin. I obviously don't want to hand him over full of poop!
Just received this pedantic email (attached in comments) which will have gone to all parents. I'm quite annoyed as my their suggestion of staff escorting parents to another toilet. My son cannot access the main school and is in a segregated area with full time 1-1. Plus I'd have to faff around getting a sign in badge. Reception are aware he's sen and only has one week left before moving schools after summer.
I spoke to his 1-1 about it and we're convinced it's aimed at us and one other parent who's baby goes on the school run.

AIBU to feel like emailing them suggesting they place a nappy bin in the toilet, buy some air fresheners and maybe get a better sealed door if the smell travels the much?

If you're putting it in a sanitary bin, then yes, you're in the wrong. In my experience as someone who works in schools, those sanitary bins are only emptied a few times a year. Certainly not often.

Just take the pooey nappy home with you.

And so what if the email was aimed at you? Rightly so, and also, you're leaving the school in a week anyway.

The email is completely reasonable, that must have been unpleasant for staff especially during a heatwave!

Tip the poo in the toilet and flush and then take the rest of the nappy home in a nappy bag. That’s what I would have done when changing a child anywhere without proper disposal facilities.

The email is fair enough.
They’re offering another option.
Why would you leave it in the bin, that’s disgusting. I wouldn’t leave a dirty nappy in a bin in my home, so why would you put it in the bin in the school, it goes straight into the outdoor bin.
Bring it home, stinking the bathroom.

OP could also make reasonable adjustments, double bagging the napping, putting the poo down the toilet. Op can use a safety wrist strap if her child is a flight risk, it would enable DS to move around different areas without risking running off. I used one when I needed it.
The school have made reasonable adjustments as the facilities are available. OP needs to meet them half way by using a safety wrist strap to access the toilets. If he dirtied his nappy in school, I doubt his 1 in 1 would bring him to the reception bathroom. They would use the correct facilities with a nappy bin provided.,

None of that is relevant because he isn't going to be there anymore, so there is no point in complaining about disability discrimination or demanding another disposal unit is bought/leased; she just needs to take the things home rather than being nasty to staff who would be putting their health at risk to deal with her deliberate decision to leave it there for them to deal with.

This is exactly the point I made in my original post and reiterated here by saying "...had this child been staying...."

Just take the nappy with you! It’s not that complicated.