A Gentile buried under the altar

A Gentile who chooses to be buried in the Land of Israel.
Although the teaching of the G-d that he was buried in the Land of Israel, his sins were forgiven, is learned from the Hikash, and the land of the Atonement was made with him, and an altar of earth, earth, earth, will be made for me. And a Gentile, apparently, is not at all with him.
But the language of the Hebrew is all, and so is the Rambam, and they did not specifically limit it to Israel.
And this altar is seemingly universal, since even a Gentile can bring a sacrifice to God at the altar and sacrifice in His name.
(Although the Rabbi Y.I.P. reminded me) that only almsgiving, but sin and atonement, are not for the Gentiles at the altar.
And also in the Maharsha in the Ketubahs, the fact that Adhar’s ashes were collected from under the altar and buried in Israel (all of Israel is under the altar for this matter) actually returned to the dust from the same place it was created, and this is a virtue and atonement. Again, this is a universal virtue, not specifically Israel.
 
So the Gentile is free from his sins when he is buried in the Land of Israel, like Israel. Or not?