why is it any less an affront to Christ to subject him to our saliva and digestive processes than our hands?
Aside from the proper signification of the priest feeding the flock and the actual consecration of the priests hands, one could easily turn the table and reduce their indifference to the absurd. When they object, ask them why it matters at all? Then start picking away at their answers. There must be some sign of reverence present
. Then look to tradition and explain that it is not arbitrary. Ask them to think about the reasons why as opposed to acting like a flippant teenager with regard to the holiest Thing on earth. Explain to them the traditional distinction between profane and sacred, a notion that has been utterly destroyed in the novus ordo.
You could also mention that there is no parity between what is of choice externally and what happens of necessity with regard to actual eating. Consequently, there is no sin where the force of necessity is present; it ceases to be a human act properly speaking.
Additionally, in the old rite of baptism, the mouth is in fact consecrated to eat the Bread of Life as well.