But this information could come delayed. When does a node say: stop I do not accept this block from this account anymore?
This is why *timing* is an *essential* part of Nxt (your clock needs to be set very accurately).
Bitcoin doesn't have a reliance upon NNTP (which is why the timestamps can vary quite a bit) but Nxt *does* (this is also a very fair *criticism* of Nxt IMO).