I heared a lot of rumours in the past months about the exchange Yobit. Not sure if they are all true, but I have used it for many transations and never had one problem. It's strange that they would hold another signature campaign, but if you're losing support you have to try and get your name out again, right?
You had no problems because not allowing people to withdraw is a very big red flag and if that happened you'd all run to every forum on the Internet to tell people about it. They won't steal your couple hundred dollars worth of crypto because it allows them to maintain a facade of a legitimate exchange and do the dirty work behind the scenes.
This includes manipulating the markets, listing scam coins for a hefty fee, most likely participating in pumps and dumps and running a ponzi scheme in the form of an "invest box". I wouldn't be surprised if they were laundering stolen coins as well.