This is a BS charge. Romney said he thought the minority opinion got it right--its a penalty and as such its unconstitutional. Romney then said while in his opinion and that of the minority of the court its a penalty, since the court majority has ruled the penalty is a tax then that is what we have to call it and treat it as--a tax.
I don't see any flip flopping or confusion--Romney agrees with the minority but recognizes the authority of the Supreme Court. Romney has promised to repeal Obama Care and Romney has reiterated that promise, despite the courts decision that the penalty is constitutional when viewed as a tax.