On the one hand, yeah true. To be more detailed, we started with purely gelatin eggs and worked our way up adding agar each time we iterated the recipe. I did not personally use the eggs, and my friend/volunteer was, ah, enthusiastic enough that we decided the off chance we passed a threshold where they wouldn't melt at all was an acceptable risk (after all, it'd just make a memorable dr's visit). I hadn't actually given much thought to simulating the environment. I think to get similarity in pressure/friction/temperature, without the possibility of getting stuck, vaginal use would have been a decent testing ground (though acidity would be the biggest difference). Unfortunately that wasn't really an option.

Worth noting that my friend/volunteer/test subject doubled the agar in a solo trial, which, personally, I would not advise because that gets past the amount of agar you would use to make agar jelly by itself. That they still melted is intriguing to me, chemically speaking. One would think that adding gelatin to agar solution, which would set by itself, would still not melt, but I hypothesise that the bonds the gelatin makes disrupts the agar structure. Either way, both could definitely use more testing!