The dealer should never be making a decision in a game of blackjack, they're basically an autonomous monkey that exists to deal cards. Basically the problem is that house will hedge its bets unfairly by not having fixed rule on dealer staying or hitting. What creates the problem is there isn't a house rule on soft/hard 17 (there aren't even soft/hard 17's, but we get to that).
I realize the game's variant is 'suppose to' be slightly different than blackjack but basically in essence blackjack but there are a number of issues with it.