Excuse me? Let me outbalance you by putting more effort into my answer than you do.
The problem isn’t really whether they’re a threat at that exact range or not. The problem is that people can come into SOV nullsec, mess around in our space and basically can’t be engaged while everyone else still has to deal with them.
Saying “just leave” doesn’t really solve the issue. We’re talking about SOV space here, not some random neutral area. If the answer to someone being there is always just to leave because they’re not an immediate threat, then there’s basically no reason to defend or contest the space in the first place.