A deendaar man cuts his beard less than a fist length.

Answer

A person who cuts his beard less than a fist length can never be genuinely 'deendaar' (pious). Undoubtedly he is a faasiq. Dissociation from a faasiq is incumbent. Nevertheless, one should not despise him. One should not initiate Salaam to a faasiq. If he makes Salaam, one may respond. In these times of massive ignorance, most people are not aware of the ahkaam. He will not know why one is not responding to his Salaam. If he is indeed 'deendaar' as you believe, then politely inform him of his act of fisq. Perhaps he is truly ignorant of the mas'alah.