Seagsl - I think the distinction you’re missing is that married priests, in the Latin Rite, are the exception and not the rule. Not all married convert clergy who apply for the dispensation are granted it. Some former Protestant clergy just become deacons or teachers in the Church – e.g., Scott Hahn.
As a rule, in the Latin Rite, the Church does not allow married clergy. However, under rare circumstances, the Pope MAY grant a dispensation to this rule, if he feels that the man in question does have a vocation to the priesthood that he did not realize earlier due due his Protestant upbringing. But this dispensation isn’t common or easy to get.
In other words, the reason for the exception is because the men in question did not have access to the fullness of Truth at the time they married and/or became clergy in a Protestant denom. Catholic seminarians, and those Catholic men discerning the priesthood, DO have this access and this aren’t eligible foe consideration for the dispensation.
ETA: Think of it this way. Most universities require students to be at least 18 when they enter as freshman. However, many will make a rare exception for 15-year-old prodigies who have demonstrated exceptional aptitude. Does this mean that universities are being hypocritical for not admitting any 15 year old who wants to apply? No, because the exceptional students do not mean that all 15 year olds are capable of college work. This, the standard becomes the rule, and exceptions are decided on a case-by-case basis depending on the circumstances.