The ruling on this and similar issues comes under the ruling on whether minor issues of Islam are addressed to kaafirs too. The correct view is that they are addressed to them, and this is the view of the majority. Hence it is not permissible to enable him to eat during the day in Ramadaan or to help him to do so. 

If a kaafir persists in his kufr and dies as a kaafir, then he will be punished for his kufr and for all the rulings of sharee’ah that he failed to abide by. This is indicated by the verse in which Allaah says (interpretation of the meaning): 

‘Every person is a pledge for what he has earned,

39. Except those on the Right (i.e. the pious true believers of Islamic Monotheism).

40. In Gardens (Paradise) they will ask one another,

41. About Al‑Mujrimoon (polytheists, criminals, disbelievers) (and they will say to them):

42. “What has caused you to enter Hell?”

43. They will say: “We were not of those who used to offer the Salaah (prayers),

44. “Nor we used to feed Al‑Miskeen (the poor);

45. “And we used to talk falsehood (all that which Allaah hated) with vain talkers.

46. And we used to belie the Day of Recompense,

47. “Until there came to us (the death) that is certain.”’
[al-Muddaththir 74:38-47]

It says in al-Mawsoo’ah al-Fiqhiyyah (4/263): 

When the kaafir is still a kaafir, are the minor issues of sharee’ah addressed to him and is he accountable for them or not? Al-Nawawi said: The favoured view is that the minor issues of sharee’ah are addressed to the kuffaar and the commands and prohibitions apply to them too, so that their punishment will be greater in the Hereafter. End quote. 

Wali al-Deen al-‘Iraaqi said: 

The correct view, which is held by the majority of scholars, is that the minor issues of sharee’ah are addressed to the kuffaar, so silk is haraam for them just as it is haraam for Muslim men. End quote. 

Tarh al-Tathreeb, 3/227 

It says in al-Mawsoo’ah al-Fiqhiyyah (9/211, 212) under the heading Selling that which is intended to be used for haraam purposes: 

The majority are of the view that everything that is intended for haraam purposes, and every conduct that could lead to sin, is haraam and the sale of anything where it is known that the purchaser intends to use it for something that is not allowed is forbidden. 

Among the examples given by al-Shaafa’i are: the sale of drugs to one whom you think will use them in a haraam manner, or wood to one who will make it into a musical instrument, or a silk garment to a man who will wear it when it is not necessary to do so, or selling a weapon to a wrongdoer or a bandit, or an animal to one who will make it carry more than it is able to. 

Al-Sharwaani and Ibn Qaasim al-‘Abaadi stated that a Muslim should not sell food to a kaafir if he knows or thinks that he will eat it during the day in Ramadaan, and al-Ramli stated this in a fatwa and said: Because that is helping him to commit sin, based on the most correct view which is that the minor issues of sharee’ah are addressed to the kuffaar. End quote. 

And Allaah knows best.