Not quite. It is not wrong for you, me, or any priest, or the pope to kneel and wash anyone's feet as a sign of service we owe all others. Well, so long as the person whose feet are being washed consents, and the parent consents, and it is understood correctly as a symbol of humble service and not some flirty thing.
The only possible wrong here is purely skewing of the rubrics. The rubrics say "wash the feet of select men (viri)" and the pope washed the feet of men and then also washed the feet of select women, instead of proceeding to the next rubric straight way.
In other words, he improvised a bit in a rite that itself is not very old: it dates, correct me if I am wrong, to 1955. And he is not any priest but the pope. Legalistically, it is not a big deal; I would hesitate to call it abuse of liturgy. Any priest that would take this example and, in what would be true abuse, ad-lib through the Eucharistic prayer would be a complete fool. Yes, we have such fools, but we can't allow their obtuseness limit good priests, which our pope certainly is.
A greater concern that I see is not legalistic but theological. Christ washed His disciples' feet in order to prepare them specifically for priestly service, not generally for a life of charity. The former understanding necessitates them being men because priests are all men. The latter understanding is novel, and does not fit the narrative of the Last Supper. That is a problem for me.
Really?
John 13:14 says " If I then, your Lord and Master, have washed your feet; ye also ought to wash one another's feet."
It is not the custom that priests only wash other priests feet, correct? So we know that the term "one another's feet" applies to the non-ordained.
Very few of the men whose feet have been washed at Mass in this ritual are being prepared for priestly service, correct?
So, since the ritual does not apply only to priests or candidates for the priesthood, what's the big deal?