My thought is training! I do not have that door on my HTT. But I have tent ends that have zip open end windows for an emergency exit. Not as convenient as a door to slip out nor as fun to play with.
I have trained my kids that the end window screen zipper is not a play toy. I still remind them every spring and periodically (more frequently when they were younger) that is for emergency use only. In my case, I remind them also that the end window zippers are always to be zipped up to the top center. This way in an emergency anyone can find there way out quickly (without having to search). To reinforce this notion of an emergency exit, we did a few emergency exit drills (kids loved it when they were young). We also discussed where to meet if they ever had to exit due to a fire or other emergency, same rule no matter the campground. It was great training for them. I have no issues with the kids messing around with the zippers. They now get bored with me when I remind them (teenagers
I would not block the door or make it extremely difficult to open. Kids are masters of over coming obstacles, so training is best.
You should watch a few YouTube videos on how fast campers go up in flames. They can be full engulfed in just 2-3 minutes in the right conditions (scary how fast), and 5-7 minutes if it takes a little time to get started.
Hope I did not scare you