Gonners,
The "rock" is the faith of the Apostles, as one of the oldest prayers in the ancient Roman liturgy shows us.
"We beseech Thee, almighty God, that Thou suffer no disturbance to shake us, whom Thou hast firmly established on the rock of apostolic confession. Through our Lord..." (collect for the vigil of the blessed Apostles Ss. Peter and Paul)
Lex orandi lex credendi!
In the East we allow married men to be ordained. Unmarried men who are ordained may not marry and this has always been the custom in both East and West. That the custom in the West is to ordain only unmarried men is a different issue, a legitimate one, and something entered into freely. No problem.