Not sure if "require" is the word I would use, though I will base my answer on your terminology.
If by require you mean, "go to therapy or this is over," then that is your choice, but certainly one that I as a PTSD sufferer, would likely walk away from my partner as a result. A choice, basically. If he is not ready to attend therapy, then his choice is limited.
If you mean you would like him to attend therapy to better himself so that your relationship can improve... that would be nice, but honestly, him wanting to go it alone isn't idiotic either, providing he has the right tools and isn't just trying to push himself past everything without the education to understand what is happening within him.
Self education is extremely powerful. To read, learn what therapists learn, to work on your own issues proactively, in your own time, can do some of the best work. Seeing a therapist every now and then, also good, as they can help in some areas, with ideas from experience, that you may not have thought of or read.
I started with therapy... and let me just say, it was useless. I got little from it and would have been in it still today. Instead, I went it alone. Yes, that decision cost me another relationship, yet here I am a decade later a much different person than the always highly symptomatic, complex, messed up, individual I was due to my own years of trauma.
All of my own healing, my recovery, my goals, were done by going it alone, self education, asking lots of questions here to strangers around the world in order to get ideas, feedback, to act as my therapy loop.
Us guys can be difficult, stubborn and more, I understand that. This will certainly be a difficult decision for you IMHO. Maybe you could see a trauma expert yourself and ask them what it is for him to expect from therapy, so you can have an informed discussion with him first?