Hey,

From SG guidelines:

Beta keys which do not provide unrestricted access to the full game in the future, guest passes, demos, and coupons cannot be given away.

Tumblestone trial gifts allow users to play few matches per day, and later access to the game is blocked. That's why it can't be given away here. So adding comment in giveaway description that it's trial version would not make it fine for winners to mark this giveaway as received. Instead could prompt support member to delete whole giveaway when it was still running.

Now you'd need to have permission from all winners to delete it.