Did he really live to the age of 103? Its possible that he lived to an incredibly old age and died the same year as his namesake grandson, but I doubt it.
I found his entry (142) in _Benjamin Family In America_ (Bicha) on page 51 (PDF available for free at archive.org). She agrees with these birth and death dates but she mentions that he died at the home of his son Nathan. But according to his Geni profile, Nathan had been dead for 18 years in 1803. It seems awkward to refer to the house as Nathan's since he had been dead for so long. It seems more likely that Joseph died at Nathan's but in a different year.
I found the grave of a Joseph Benjamin buried in Egremont who died in 1803 and I think the death dates of the two Josephs were confused. Bicha says that Nathan had a son Joseph born in 1763 and whose wife and son Orson match up with the entry at findagrave. That makes the Joseph at findagrave the grandson of this Joseph.
Person Birth Year Bicha Index Number Bicha Page number
Joseph Sr. 1699 142 51
Nathan 1737 381 103
Joseph Jr. 1763/4. 860 186
https://www.findagrave.com/memorial/71307024/joseph-benjamin
https://archive.org/details/benjaminfamilyin00bich
This profile looks like the grandson at findagrave and the wife's family matches Bicha.
Joseph Benjamin
Except instead of being Nathan's son, he's Nathan's grandson. Geni shows inconsistencies with the latter relationship so maybe the former is correct.