Is there any Sharia or customary basis for the strictness regarding touching the beard, on the pretext that it is akin to touching the face and cheek? Was anything reported from the Salaf that supports this, or did the Prophet, peace and blessings be upon him, approve of those who touched his face, or his cheek, or his beard, or the hair of his head?

Touching the beard is permissible. It was reported in the story of al-Hudaybiyyah that Urwah ibn Masud began speaking to the Prophet, peace and blessings be upon him, and every time he spoke, he would take hold of his beard, while al-Mughirah ibn Shubah prevented him from doing so out of reverence and respect for the Prophet, peace and blessings be upon him.

The beard may also be grasped as a form of insult, as Ibn Masud did to Abu Jahl on the Day of Badr.

If a person dislikes having his beard touched, he should not prevent his father or grandfather from doing so, as long as the act is permissible.