Praise be to Allah.
If a Muslim does this, it is haraam and there is no doubt concerning the prohibition on doing that, because of the report narrated by al-Bukhaari (2236) and Muslim (1581) from Jaabir ibn ‘Abdillah (may Allah be pleased with), that he heard the Messenger of Allah (blessings and peace of Allah be upon him) say, on the day of the conquest, when he was in Makkah: “Allah and His Messenger have forbidden the sale of alcohol, dead meat, pork and idols.”
Regardless of whether he feeds it to the People of the Book, or he feeds it to dogs, or does anything else with it, selling and buying pork is haraam, and its price is also haraam.
Ibn al-Mundhir (may Allah have mercy on him) said: The scholars are unanimously agreed that selling and buying pork is haraam.
End quote from al-Awsat (10/20).
Ibn Battaal (may Allah have mercy on him) said: The scholars are unanimously agreed that selling and buying pork is haraam.
End quote from Sharh Saheeh al-Bukhaari (6/344).
With regard to eating pork, that is also haraam, and the prohibition thereon is well known from the Book of Allah, the Sunnah of His Messenger, and the consensus of the Muslims.
With regard to the one who does that, whether he does it only once or more than that, what he must do is repent sincerely to Allah, may He be glorified and exalted, and seek His forgiveness for what he has done in the past, and he must never do such a thing again. He should not compromise for anyone with regard to the religion of Allah, or try to appease anyone or be kind to him by doing that which involves disobedience to the Most Gracious, may He be glorified and exalted.
If he wants to offer food to anyone, Muslim or non-Muslim, he can give them food that is wholesome and halaal, and he can give him to drink that which is wholesome and halaal; he should not help him to disobey Allah, may He be glorified and exalted, and he himself should not disobey his Lord in order to offer food or drink to someone else.
And Allah knows best.