A lot of people seem to be offended by the comparison of the pregnant Mary to the Ark of the Covenant.
Okay, fine. Let’s pretend that she didn’t serve as the Ark and Throne of God, or that magically the Ark would stop being the Ark when Jesus was delivered into His mother’s arm. Fine. We’ll pretend that.
Now, let’s think of Joseph. As the head of a family and as the unacknowledged heir to the Throne of David, he could be a priest in various ways, including in the line of Melchizadek. He was chosen to live in the same house with God Almighty incarnate.
So the stable in Bethlehem, the home in Nazareth, and every camp and rest stop and Egyptian house where the Holy Family stayed, were basically the Tabernacle and the Holy of Holies.
In which Joseph served, every day of his life, year in and year out.
Now, all the priests and Levites lived under special regulations, but there were a lot more rules for them when priests were serving in the Temple.
Among which… was the rule that a priest could not have sex with his wife or anybody else, because otherwise he would be unclean and could not enter the inner temple area, much less the Holy of Holies.
Similarly, of course, the priest’s wife had to remain continent while her husband was doing his stint in the Temple.
Priests served only a few weeks every year. Joseph served and spent time with Jesus every day and every night.
Please tell me how he and Mary could have possibly had any interest in getting it on, when they would have to have abandoned the Holy Child and their house, or spent a whoooooole lot of effort getting ritually clean afterward.
Much less afforded the sacrifices.
Much less attempted to explain why members of the Tribe of Judah were offering priest sacrifices.
OTOH, considering St. Joseph as someone acting as a priest connects his service to Jesus to his protection of Mary. The woman a priest marries “must be a virgin,” according to Leviticus 21:13-14, and “a virgin from among his own people.”
Now, the interesting thing is that of course Jesus does approach people whom a priest, or anyone attempting to remain ritually clean and holy, would not approach. Since He is God and ultimately holy, He doesn’t mind about touching the dead, or the lepers, or a woman with a sickness of blood, or those demonically possessed. He brings ritual cleanness and holiness by His very being (although He does advise the lepers to obey His law and go to see the priests).
But there’s no suggestion in tradition that He got rid of the continence regulations for priests. Instead, we hear of the earliest Christians insisting that bishops refrain from having sex with their wives, while ordinary Christian couples observed continence during fasting periods and fasting days, just like Jewish couples.
So logically, Joseph wouldn’t have been doing anything with Mary, much less begetting other children with Mary. Because even if she wasn’t the living Ark of the Covenant, he was a priest in Temple service every day.