And why do "true believers" have a "moral obligation" to shun commerce with gay people but not with those straights who facilitate the supposed sinfulness of gay people by having commerce with them?
If we accept the premises of "true believers," the situation is analogous to prostitution. "Good Christians" may not support the "prostitutes" themselves.
Instead they support the "pimps" - the enablers.
Which, in turn, begs the question... Which of them is worse? And what about my fellow Catholics whose physicians supply women with contraceptives?
Should these Good Catholics not at least ask their physicians whether they participate in such sinfulness?
Only then can Good Catholics refrain from encouraging those who aid and abet sinfulness in others.
And if physicians refuse to reveal their profiteering promotion of sinfulness, should Catholics not shun them "on suspicion?" Better to err on the side of safety. No? Hold your moral ground! Shoot on suspicion!