Blocking spam is not selfish, no.

I'm not sure I'd call it selfish. There are users with particularly distasteful opinions that I prefer to downvote when I see them expressed. If I blocked them, then I wouldn't be able to help shape the community in a positive manner.

That's fine to do once you've reported it: you've done your part, there's no value still seeing the post it's gonna get removed anyway.

Is this not a slightly selfish action? It solves the problem for you, but doesn't make the community better for everyone. I feel like blocking users should be reserved for issues like harassment, not spam.

This is an aspect that I had not considered. Even thinking about it now leaves me unsure of the best way forward.

Specifically, whilst it's a valid argument that blocking the user only solves this for me, and not blocking would help me see if the issue was dealt with, I feel that leaving the user free to roam across my screen is impacting me directly and if I'm not a moderator in a community, it's not my place to second guess their decision to leave such a user and post in place.

In other words, I'm stating to a moderator that I think that this post is spam and should be dealt with accordingly, but if you leave it alone, that's your choice.

I moderate several communities outside of the fediverse and spam in my communities is a one-strike ban. That's not what everyone does.

Having now thought through this again, now in more detail, I'm comfortable with blocking the user.

I don't and will not use blocking for users basically for that reason, it doesn't actually solve anything it's just pretending things are okay for you when they aren't for everyone else. It's probably the reason why reporting doesn't happen as much as it should.

Even in harassment it is particularly useless because even though you stop seeing them and getting notifications they can continue replying in your threads, they can even use that to turn people against you. If it at least prevented posting and commenting on your profile I'd use it in those situations, but as it stands it doesn't, so it's useless to me, because if somebody is harassing me, the last thing I want to do is hide them while allowing them to keep harassing me, it gives them mote opportunities to cause trouble and removes my opportunity to report them for that trouble.