Wow there's a lot of places I can bring this for instance
Even if we ignore that blatant loophole of, "you specifically said any sex act, so any sexual act that does not qualify for this, legally cannot then be considered a sex act" what's defined as a physical act? Is it an act done to a physical body? physically touching another person? If they have to be touching does that mean I can cyber someone still? If I don't have to be touching then again, that loops back around to "is seeing or participating in a pole dance counting"
the letter of the law is what matters not the intent, the writing is "celebrate marriage ceremony" with no specification to what kind of ceremony just that it in some way can be referred to as a marriage, if it has to be legally binding, and a lot of things. A malicious enough actor could 100% push for letting kids have pretend marriages counts, I can already imagine the phone call to a second grade teacher who didn't care that greg and bob had a fake wedding but greg's homophobic mom does.
Plus the opposite, you don't need to have a CEREMONY to have a MARRIAGE, the ceremony and the paperwork are separate, elopement for instance doesn't have a ceremony. There's a reasons laws have to be like whole documents, you have to be REALLY specific or someone is going to find loopholes and technicalities. A malicious actor could 100% read this and argue that because no ceremony was held, anyone who knew but did nothing did not violate the law as they were not the ones to sign the paperwork. No celebrating a ceremony, no charges for the rest of the community that enabled.
This one I missed before but you specified "participate in a marriage ceremony for anyone under the age of 18." fails to carve out any exceptions for anyone at the ceremony, leaving the 7 year old dragged along by his mom to the ceremony, the 39 year old mom of said 7 year old, and the 12 year old bride equally at fault in the eyes of the law for the same crime as they are ALL participating. This is the same kind of wording on why victims of this kind of stuff in reality do not come forward, because there isnt a difference made between victim and abuser.
Adultery is only made illegal if you get married, you can still cheat on your fiancee or boyfriend, or whatever with zero repercussion and that's not actually important I just think its really funny.
I won't respond further and again, I'm not expecting to change minds, I just like being pedantic and know that laws are only as good as their word, it doesn't matter if it shouldnt do something, it matters if through the wording, can it be made to mean something. If it can be twisted in a law, it will be twisted, even if you think "no one would be that malicious or cruel or stupid" there will always be that one person who proves that wrong. "well technically" isn't just haha pedantic, thats how people actually interact and interpret laws
Also the fact that you'd also need to be able to prosecute these laws would create its own challenges. Interesting fact, if punishment for a crime is seen as too severe, even if they are guilty, people are more likely to mark them as innocent or not report the crime because sure you're pissed you got cheated on, but are you actually "sentence them to multiple years in prison" pissed?
Honestly I think this is a really fun thought experiment on how meanings can be twisted and how lack of clarity in law can lead to accidental horrors being unleashed and how enforcing a law if people disagree with the punishment can be really tough. I don't know anything about you or what you stand for or anything, all I know is it's fun to take a law and go "whats the worst possible reading of this that would still be technically valid"