That I agree with. I think I misunderstood your post as you thinking the UCI rankings is the one true 'objective criteria'.Sure you can disregard UCI rankings and say TJV was better than UAE (which it was in my opinion as well). The only problem is when folks try and invent some "objective" criteria, some kind of math which would cover a specific scenario but fail to realise you would need to test every model against all the other possible circumstances and make sure it works best in average for all scenarios. Just because we have a feeling TJV was better than UAE it doesn't mean UCI ranking system is necessarily bad or misconfigured - it's just an outlier which gets statistically compensated over time.
So yes, everyone can say TJV was better but you're going to have a hard time proving that mathematically...
You can of course find strong evidence for a team being the best by looking at rankings or subsets of rankings or even very subjectively handpicked selections. But not proof in any mathematical sense, as you rightly point out. Any attempt at determining the best in a sport as diverse as pro cycling will have some degree of subjectivity anyway.