first thing first - I don't understand his logic of if something was wrong you wouldn't get it out or remember it - that's his job to check in and make sure you remember it and are able to get it out.
some people do go flying and are unable to safeword, it is up to him to recognize this is happening and bring you down, safely.
Safe words are a gauge used. No and stop can be simple safewords. Universal is mayday. However you are confusing him with the no and stops if you don't really mean it. One day, it could actually mean no and stop and he won't listen.
I'm NOT saying he isn't aware of you or your body I'm just throwing out the worse case here.
so you can be somewhat prepared and have tools in your dynamic to prevent such.
There are people who don't play with safewords. Where there is implied consent. Where they have yt?talked and talked and talked some more and everyone involved knows what boundaries they should not cross. They can tip toe to them, but never cross them
In short, if you want a safeword and he says no then that's an issue. You have to feel safe and he has to ensure that safety. Period.
talk it out.
explain why you want a safeword. How it affects you when you say no and stop and how you don't mean them but one day you might.
does he stop on no and stop? If so, that's good. He should. He needs to check in, make sure you are ok.
if you are unable to respond then he needs to bring you down, find out where you were headspace wise, and what to do and not do next time.
All play comes with risk. We tap into emotions, mentality, and physicality. It has an affect on the brain. However, play can be safe from causing permanent damage only if you know what you are doing. Unless permanent damage is something you seek, then that's you and you do you.
Also, not Making him do what he doesn't want to do? What about you wanting something and he says no. That's a two way street there.
Making sense? Sorry if I rambled.