In Shwetambar Jain tradition, a sadhu directly feeding a sadhvi is generally not considered proper. Jain ascetic conduct keeps very strict maryada, especially regarding male-female physical contact, and food is to be taken in the prescribed way, not through personal feeding.

So, in simple terms:

• Direct hand-feeding by a sadhu to a sadhvi: generally not appropriate
• Any exception or special allowance: only if it is clearly within the maryada of that sangh/gach/acharya
• Physical contact or a casual display of closeness: should be avoided

About posting it on social media:

• If the act itself is not appropriate, then posting it is also not appropriate
• Even if the scene is harmless, ascetic matters should not be shown in a way that causes display, gossip, disrespect, or maryada-bhang
• Only post if it is proper, permitted by the sangh, and respectful

So the safest Jain view is: do not do it, and do not post it unless it is clearly sanctioned by the relevant Jain authority and fully in line with maryada.