If he did regret it he would not have been "enlightened" (as was claimed) because that decision to leave them was prerequisite to his journey into "enlightenment".

If he truly did regret having orchestrated the circumstances which led to his "enlightenment" than that would imply that he felt he had lost something so significant that it actually mentally/spiritually hindered him, and if that was the case he wouldnt be able to become "enlightened".

The buddha was about giving up attachments, including those to his own family.

Do you regret you have to give your money to buy food?

Do you regret you have to burn gas to power a car?

Do you regret you have to work in order to live?

I dont.