Fighting doesn't work like that. People want to break down every component in its own little box and then try to compare skill for skill but it's the entire package that matters. Jon is a highly skilled, highly intelligent fighter but he is also getting old. He has lost speed, he has lost creativity, he has lost desire at times. Tom may never have the IQ or the creativity or the diversity of prime Jon Jones but he has the things that matter in a real fight and that is ridiculous speed for his size, heavy hands with amazing accuracy, and maybe most importantly, he believes fully that he can beat Jon Jones. He has a trifecta of Jon's kryptonite which has already been exploited by Reyes and Gus. Jon knows this and that's why he won't fight him. (Also why he wouldn't fight Frank, but Aspinall is more of a problem than even Ngannou)