I don't really see a problem with it myself.
The gems that get bumped up that have finished are usually bumped with a revised "buy now" price and once they get to what is considered the lowest the bumping doesn't happen until they start to drop off the page where someone might be interested in it.
In that example you posted the gap between bumps is about once a week, it's not like it's a daily process. Some people may say it's "confusing" but in the auction board you can't edit posts, so the initial post can't be modified to say that the auction is over and that there's a new "buy in now" price or a reduction in cost, so there's not really a lot of choice except to bump.
Also, if tiptopgem annoys you on the forum so much, why don't you just use the forum's ignore user function?