No, it shouldn't be this hard. Unfortunately you're working with a system that is on its knees and stretched far beyond capacity, though.
The local authority can and indeed should consult with your preferred school that is out of county. You can also approach them yourself to sound them out about your son's needs and whether they feel they can accommodate him. It will ultimately need to be done through your LA though, but you can make your own enquiries.
You've talked about your son wanting to be at school with his friends. Is this actually a viable option? In your view, would he be able to cope in mainstream school with a 1-to-1? It's not really clear how long the school tried this for. Was the persistent disruption still a factor? If you think the school did not give that option a proper chance then you absolutely have the right to push for it, whether at his current school or the other mainstream school, since it's written in his EHCP. However, if it is genuinely unmanageable for your son and for the school due to the level of disruption he causes then you do need to move on from that and put your energy into having him in an environment he can manage, whatever that looks like.
As a parent, I've been in a very similar position, I gladly accepted the AP as an interim measure. My preference was actually for a permanent EOTAS package as school simply wasn't the right environment for my child, although the LA will only go for that as an absolute last resort. While he was out of school I got him involved in quite a few extra curriculas to make sure he was getting the social contact he needed with peers. In the absence of any suitable school in an entire county, the LA consulted, at my request, with an independent school out of county, who accepted him, and it's honestly worked out brilliantly.
It's a hard road. I genuinely sympathise with the schools and LAs who are working in very difficult circumstances, but at the same time you need to be like a dog with a bone about getting things done and call out the LA when they are not doing what they should be doing or not meeting statutory timeframes.
If you want to give the other school a go and see how that plays out then do that, but if it isn't working then make sure the LA consult with your preferred out-of-county school, and submit a formal complaint if they fob you off.
If you haven't already, get in touch with the virtual school. I had them attend some annual reviews and they were very helpful in terms of having an additional advocate in the room.