I’ve always been of the mind that those food cautions in the Bible came from the fact that shellfish and pork both spoiled fast in the dessert and was put in to keep people from dying of food poisioning in the days before refrigeration. I could be wrong and if I am then I’ll be there right next to you.
Two points. The OT Leviticus explains that God holds all nations (read -non Jews) accountable to a morality standard that excludes homosexual acts. God claims he removed these prior nations from the land because of homosexuality and other sexual immorality. He did not remove them because they ate shellfish.
Further, in Acts 15, a council met and declared that the requirements of the OT law was no longer an obligation for Christians EXCEPT for sexual immorality among other things which also did not include shellfish.
The argument that shellfish and homosexuality are treated the same by the OT and the NT is false. Shellfish did not cause nations to be removed from the land and was not specified by the early Christians in Acts 15.