Me personally? No! Back on PS4, my alt joined a power specifically for "legitimate" PvP. You must understand, I'm an immersive, role-playing CMDR, to the point of nerfing myself in many ways. I've decided with my new PC CMDR that I'm not going to pledge to any power, which means I'll never own a PP module. If I change my mind, I'll pledge only to one or perhaps two at most powers, and those powers would be allies (most likely Hudson and Winters since my current CMDR is loyal to the Federation).And I'd ask you, if this was in Open in Powerplay, would you block other rival pledges?
If yes, what you describe here in a Powerplay context is exploiting the block function.
But I doubt I'll change my mind...
Having said all that, PP is a game that can be played from Solo and PG, and even when I used to play pledged to Arissa on my alt, that was on PS4 where you could do nothing to get to me (except buy a PS4 yourself), so I'm not sure how blocking breaks PP.