[headstamp 2]

Maybe he has bad knees.

[lulu16]

I have gone up and helped priests as they prostrate themselves before the cross sand have trouble getting up during Good Friday.

If he doesn’t that is not for physical reasons, he has some ‘splaining to do

[CharlesOConnell]

I'm Man #2 who never kneels. I can't, I have asked in prayer to do so, I am not being given any relief, I'll never get a hip operation, surgery is permanent, so I get out of the way of anyone, and I bow as profoundly as I can during the Consecration.
 
I am a sinner like the tax collector who can only bow his head during the Pater Noster and ask my Blessed Lord please to excuse me in view of His infinite merits.
 
I once sat behind a woman in a Trad veil at the old Oak Park Sacramento parish of the Immaculate Conception, in a predecessor to the FSSP mass, at that time called Ecclesia Dei. The woman was glaring around at any slackers who might be neglecting the proper canonical response motions. I don't think she found any, in any case, the other Mass attendees would appear not to have noticed the lady's playing the soul cop, they were all engaged in participatio actuosa (Pope St. Piux X, Tra le Solicitudini, St. Ceclia's Day 1903).

[ebb tide]

Maybe he has bad knees.

Cardinal Bergoglio kneeling for a "blessing" from heretics:

Pope Francis kneeling to wash muslims' and females' muslims feet on Holy Thursday:

Pope Francis kneeling in an Anglican shrine on November 28, 2015:

[Vigilanteman]

Maybe he’s like ObaMao and just doesn’t wish to recognize a higher power.