All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
A son has to obey his parents in the matter of his marriage, otherwise he would be a sinner. Marrying a particular woman is not an obligation while obeying one's parents is an obligation. Obeying them is also a kind of being kind and dutiful to them, which is an obligation. Listening to them becomes more important when the parents have a legal reason, as mentioned in the question, to object to the son against marrying a certain woman.
However, it should be mentioned that parents should not blame their daughter-in-law or anyone else without sound evidence, such as seeing or hearing directly or having trustworthy witnesses. Know that blaming of the matters mentioned in the question has very serious effects in the Sharee’ah. So, the Sharee’ah puts more precautions in these matters than others.
Know that acquiring an educational degree or being of age is not among the conditions of marriage. The important qualities considered are that the husband should be physically able to satisfy his wife and bear her expenses.
We advise our brother to obey his parents. In fact, Allah will give him better than what he has left for the sake of Allah.
Allah Knows best.