It's because the winner has been drawn and contacted, but not verified. We await the winners Steam URL via the message form on the givelabs website, so we can verify all entries/not a multi-account and be able to gift the copy on the release date. We'll draw another winner if they fail to comply. So that's why the winner isn't public yet. I assure you the giveaway is legit and the guy was drawn on the first roll.
We've however noticed that there are only 130 members in one of the Steam groups, yet 246 individuals has pressed the entry button implying they joined it. In accordance to the participation rules stated in the TOS popup on the giveaway page, we maintain the right to pick a winner who've not left the group/s or discord server if they've claimed those entries prior to winning as that'd be to cheat the system for a larger chance to win at the cost of others legitimate entries.