Is it considered an act of disobedience (عقوق) for a son to avoid sitting with his father, limiting interaction to merely greeting him and kissing his head in the morning and evening, out of fear of hearing his father mock the son's religious commitment?

The right of the father is among the most emphasized rights, and his beneficence cannot be repaid except by emancipating him if he is enslaved. One must bear patiently with any displeasing behaviors or words that may emanate from the father, and treat him gently, seeking the countenance of Allah, knowing that Allah does not let the reward of righteousness and beneficence towards him go to waste. Try to advise him in a manner he understands; if he responds, then praise be to Allah, otherwise, continue in obedience to Allah and in beneficence towards him. There is no harm in refraining from sitting with him if it might lead to corruption.