Not every Episcopal or Lutheran clergy who converts to Roman Catholicism is ordained. Many seek ordination and few of those are selected; less than 1,000 worldwide since Pope John Paul IIs 1980 Pastoral Provision, which stated in part:
"the Holy See has specified that this exception to the rule of celibacy is granted in favor of these individual persons, and should not be understood as implying any change in the Church's conviction of the value of priestly celibacy, which will remain the rule for future candidates for the priesthood from this group."
You probably also don't realize that prior to ordination, said converts must agree to adopt the discipline of celibacy for the remainder of their lives should their spouse precede them in death.
That is the Orthodox practice for all married clergy as well.