I think you should, in good conscience, ask yourself how likely it is that this action will spread the virus. It is what we should all ask ourselves every time, regardless of "rules" which cannot cover every individual circumstance.
So what you consider is what is the level of infection in his area? How much does he mix with others? How will he get to you? If the incidence in his area is low, he only goes out for food and he's coming in his car, the risk that he will add oread the virus is minimal.
Then think about his short break with you. You are in an area of high infection. How much do you go out? Will you and he go out while he is with you? Again his travel arrangements, will he mix with others? Will he be mixing when he gets home again?
Depending on the answer to these question the risk of his spreading the virus is moderate to very high.
If it's high or very high then I would suggest that the good of others trumps his need for a break and your need to support him.
Sometimes we need to use our head rather than our heart.