The 3/5 wording is not part of the 14th. Giving that that wording was an anti-slavery compromise, and the 13th outlawed slavery, it wouldn’t even make sense.
I was basing my argument solely on Article 1, not the 14th Amendment, which basically mirrors the language of Article 1 but dropping the language of the 3/5ths compromise. And as you say, unlike some racial demagogues, the 3/5ths compromise was an anti-slavery measure.