I had one guy do that in a no-reserve auction.....which is a no-no w/ ebay! Pissed me off at the time because I was the high bidder and he didn't specify he had the option to do so. So I complained to ebay about it. Don't know if he got the boot from there or not......but yes, it sucks.
If the bike and/or parts are for sale on the street as well as ebay, they should put it in the ad saying it could end early so there aren't any surprises.