Be careful with bit.ac. I heard that their users cant withdraw their coins from the site and their support is not answering any emails. Im not saying they are but that might a start of an exit scam.
Where do you get the information about the user's bit.ac can not do withdrawal of bitcoins? You must give us more information about your claim, it will makes everything clear for user's bit.ac because what's i know about bit.ac everything is fine never find the problem and i never find the complaint about issue on withdrawal on there. Thank you.
No, not everything is fine on bitac, there are so many issues and reports against them, dont know why they encountered it when others don't here's a link from that issue.
https://bitcointalk.org/index.php?topic=2010422.0And there are some issues also matters about bitac except withdrawal some are login issues etc.