In all honesty, the "gay marriage" part is no more (or less) a "public scandal" as we are using the term than an Orthodox person "married" in a non sacramental manner by some ecclesial community, at least insofar as The Church is concerned. Neither are marriage, Alex, and both bar one from communion.
I have a friend who has been a Latin priest I'd say 50 years. He always maintained that once a parish got to 200-250 families, it was time to open a new one otherwise the fact of "community" of the assembly of the People of God, gets lost.
There is a distinction. For sure, when an Orthodox or a Catholic is '"married" in a non sacramental manner by some ecclesial community' (or by some state functionary) it is not a marriage and should the question arise, the Church will annul the union.
However, a homosexual couple that is "married" under some legal construct cannot even ask for annulment.
In the first case the Church would presume a validity and working from that assumption will discover nullity. If the purported marriage was not sacramental, the discovery process would complete almost as soon as it started, but still it is a process of discovery that starts with presumption of validity. For example, if such spouse does not ask for annulment, the Church views them as married couple. If the canonical invalidity of their marriage comes to light, the Church will encourage them to consecrate their marriage. I don't think they will even be asked to separate for a while (correct me if I am wrong).
No such presumption can be made about a homosexual couple.
That is, of course, in complete accordance with the natural law. When a man fornicates with a woman, their sin is in yielding to a natural impulse, which is in itself healthy. When a homosexual act is committed, the sin is in the homosexual appetite itself, and secondarily in the lack of self-control. It is therefore a greater sin because it is a compounded sin.
Another aspect is not about the canon, but about the pastoral duty of the Church. The governments do not attack the Church for doing the sacraments (yet); they attack the mankind, really, and the Church at its forefront, for opposition to homosexual sin. Naturally, the Church responds to the particular attack that is underway.