What does the House offer to make up for this strange rule?
Do they offer something like 2:1 BJ payoff etc.? You must know all the game rules before an edge can be computed.
If the game is standard with the must hit 12 rule than walk away. That game is bad enough for basic strategy flat betters, but suicide for counters. During + counts you would have to hit your 12 against any dealer stiff when you have larger bets out. The higher the count, the worse this rule becomes.