1. Your own sense of absolute certainty notwithstanding, it is not de fide and binding on anyone else's conscience that attending a non-sede Traditionalist Mass (or even a Novus Ordo Mass) is a violation of the 1st Commandment. It is an unsettled matter of opinion.
Your opinion. He said 'against his will', so obviously his conscience objects and he does not share your opinion, unless he chose his words poorly. Do you think that one may do something that one believes to be a sin and remain free from guilt?
Oh, of course, Mr. Catholic Martyr-wannabe, you are the only person on this board who would not falter under threat of death.
I never said that and you're putting words in my mouth like so many others on this board. It is transparent calumny and not very classy.
You know that it is wrong to bow before idols or any false gods, even under pain of death, how much more so attending something you believe to be false worship when your parents tell you to?