i'm afraid not. how is it different from switching to solo? i totally get your point but my point is that that ship already sailed with modes, and frontier not leaving the tiniest split open for you to make a case here.
if they change this, then maybe!
Why do players object to being shot at in an opt in feature that explicitly allows being shot at in a mode that is ED at max possible player interaction?
In the end it comes down to intention- PP groups outwardly say 'we play in open' but several times have been caught out using blocking to circumvent rivals. And in Powerplay being true to your word means a lot since you are in a competitive feature in a game where everyone defines their own rules- sometimes having imposed limits has to be a thing for a feature to work to its fullest.
Its like having a football league where every player defines how they play and what is acceptable. And because there are so many ways to get round each other it causes a great deal of dissatisfaction when the sole mode for interaction can be nullified for dubious reasons. Its like a striker disallowing a defender if they don't like being tackled. Outside a competitive game I have no problem people picking and choosing, because no underlying gameplay is stopped by blocking.
If you have a rival that posts 'hehe! Power X is not happy with us, lets block them and use multiple wings to really UM / combat expansions' thats exploiting the feature. Blocking intercepting players when you are delivering fort supplies is not playing fairly in that mode.
This is why the block feature is currently too blunt, and needs a way to pare down how its used at certain times (like Powerplay).