OP, that would be similar to saying it's okay for someone to have sex with a child or with a goat, "as long as they are committed to each other long term." Just because there is love, consent, and longevity to the relationship does not magically make the act itself okay all of a sudden. Now, I'm not saying homosexuality is the same as pedophilia or bestiality, I think they are all their own deviations of how our brains were naturally designed to function.
However, I will concede that back in Moses' time, the relationship structure between homosexuals was different than it is in today's society, similar to slavery. Slavery was very different in Bible times than compared to in the early years of the United States. Likewise, homosexuality in society was much different in those times as it is today.
Also, one must remember that the law was meant for the Hebrew people at that time period, not for all people for all time. Christians in fact are claimed to no longer be under the law. This is why we can eat shellfish and we don't stone our children for having sex out of marriage. I will also agree that it is a bit unfair that even though many laws in the Torah are now disregarded and not followed, people still like to hold onto the "gay sex is an abomination" clause as if it is some exceptional rule that will never change. Basically they're saying, "We can now eat shellfish and we don't have to stone people anymore, but that gay sex thing, that still stands" It's a bit hypocritical. And they try to justify it by saying some are cultural laws and some are moral laws, but the stoning stuff would fall under the moral laws, so I never understood that logic.
Unfortunately, there are other verses outside of the Torah that appear to condemn homosexuality, although I have heard convincing arguments against those verses meaning what people think they mean. It's an interesting discussion for sure.
So while I think the premise of that poster is wrong, I do think there is room for discussion about all of this for sure.