Again, that is an incorrect assumption based on very inconsistent (BAD) data.
Are you trying to say no matter how many watts you put out and regardless of the weight you will arrive at the top at the same time? That is just ridiculous, everyone would have very similar times up the mountain and that is not the case.
I bet you could run 2 different Zwift accounts using the same power source with 2 different weights and arrive at the top of the mountain at different times. This is the test you should be doing. To also make it even better you would also capture the data using another device or app for comparison. You should also use the TT bike since you would get no drafting benefit.
You are trying to use a very inconstant wheel on trainer and you are trying to compare the 2 using perceive effort and HR from 2 different days, which is just bad testing/science.