And why is that so? What hasn't still convinced you?
Colliding with Xebec doesn’t prove he’s equal.
Luffy did that most of the time with Kaidou before being defeated — and even killed — by him, the same with Yamato.
Xebec also doesn’t have enough reason to go all out with the goal of killing Harald, when what he actually wants is to use him. Subjugating him by force was an option rejected when Kaidou proposed it to him. So it’s hard to claim equality between them here. If it were something like Base Kaidou vs Big Mom, or Roger vs WB for three days, it might make sense. But a clash between the two? That’s not nearly enough to say they’re at a standstill or that they’re equal.