I wouldn't find myself in that situation. As I said, I've flown a ton of miles and miraculously, in my decades of flying I've never had to get up during a "fasten seat belt sign". Ever. I've been "uncomfortable" but never an "emergency." And the uncomfortable situations have been during turbulence where it was not possible to use the restrooms.
So, it's hard for me to "put myself in his shoes" because it has literally never happened to me. I always use the restroom before getting on a plane, just in case. Now, perhaps he had a tight connection, but this isn't mentioned either, so probably not the case. And, it wasn't even a "major" delay. 30 minutes? Nothing. Happens all the time.
I'm not kidding when I say if you get "urgency" that bad you should wear Depends.