Love comes in many forms. For all we know teach is doing all this for love too because of what the WG did to his mother.
But Oda has a specific message about love. The bad guy cannot be motivated and empowered by the same thing as the good guy. That make love itself a non-factor and not worth anything if it means the same thing to both sides. To Oda, Love is a good thing, so he won’t have the bad guys also motivated by the same thing the good guys are.
The problem with your lineage factor theory is that it’s TOO nebulous. Controlling your lineage factor is like, well what’s even the limit of that? Can you make yourself a different race? Can you make yourself a woman when you’re a man? That statement is too broad
in my theory I dont say “Buccaneers can control their souls”. I say Buccaneers can split their souls. That’s it. So it seems like they have multiple souls. And that one simple ability can produce different results of Kuma resisting mind erasure and Teach can eat two DFs