There's members here that seem to think that breathing inside a protestant church is active participation and scandal.
Do it. It will not be scandalous in this day and age. At least that is my opinion.
Vladimir- please be more conscious of what you say and how it is said. First of all the air of, "Do it, its not as bad as everyone is making it seem" is a bit dangerous. This is indeed a sensitive matter, and regardless of how the majority of Catholics (especially NO and NO friendly) view it and Church law, should be treated with care.
Secondly, this is a completely different situation than your other thread about participating in a Protestant church with your musical abilities. Do not justify what you do that is harmful, by suggesting that someone else participate in another manner.
Lastly, the impression that the advice of those who were cautioning you against your participation in protestant worship is likened to breathing inside a protestant church is insulting. You obviously did not come here for advice, and chose to stick to the advice of someone else; in this case I presume it to be your FSSP priest. Sadly, this fact of him being a member of the FSSP only makes sense of everything.
Caution on the side of Christ and His Church always. Be more mindful of the harm and scandal which can be done Him and His Bride, and not of those who reject and hate them.