Well you have to understand how Flippa makes their money to understand what you're seeing.
First of all, this is an anti-snipping features that many auction marketplaces use (not eBay). This encourages bids during the duration of the listing and not bids during the last seconds of a listing from a bunch of lowballers trying to steal shit.
Secondly, Flippa gets a fee for listing the auction and then takes a rake on the final price. It is not in their interest to allow bidders to all sit around and try to snipe auctions during the last seconds of a listing, thus getting listings for a lower price. So if you bid during the last 4 hours of a listing then it extends another 4 hours and emails are sent to all people bidding or watching this listing. This gives them ample time to come in and re-bid thus making Flippa more money.
I'm not sure what you mean by a suspicious bid towards the end that keeps extending the listing. You need to understand that on Flippa there are filters for sorting listings and one of the most popular filters is Ending Soon. That will show all the listings ending in the next hour to two hours depending on the volume of listings. It's very common for auctions to get bids once they get to the first page of that filter because there are hundreds if not thousands of eyeballs on the listing for about 2 hours. If someone bids on the listing then it gets dumped off this first page and extends 4 more hours. Once the listing gets back to the first page then thousands of eyeballs look at it again and it might get another bid or someone may respond to an email that they've been outbid and they'll come in and bid.
Also besides coming up on the filter Ending Soon page, Flippa sends an email to all outbid buyers when a listing is ending soon to encourage them to come back and bid again. So besides ending listings getting great exposure on the Ending Soon page they also get exposure from an email blast Flippa sends to involved parties to come and bid again.
It sounds like you should study the Flippa system a bit more before throwing out accusations and innuendos. It doesn't work like eBay and last second bids won't snipe a listing.
Unlike eBay, Flippa knows where it's money comes from and it's not from the buyers. Sellers pay almost all the fees and a lot of times all the fees so getting the most for a website is good business for the website seller and Flippa. Buyers need to adapt or go play on eBay.