The source for that claim seems to be Gotham Government Relations,
Stuart Seldowitz, former Director of the National Security Council (NSC) under President Obama and former diplomat for the U.S. State Department serving during five presidencies, is our Foreign Affairs Chair
You can see the other elements of this claim in "Interview with Stuart Seldowitz on Israel-Hamas War" by BitChute
I had to choose from among all the wonderful experience you have shared with me on your resume and the most relevant of course seems that you were the Deputy Director/Senior Political Officer in the US State Department's Office of Israel and Palestinian affairs from 1999-2003.
Gotham Government Relations since publicly terminated relations with him, and they've offered to sue Seldowitz on behalf of the street food vendor.
On the title
Form the interview in BitChute he claims he has the title,
Deputy Director/Senior Political Officer in the US State Department's Office of Israel and Palestinian affairs
Looking it up, this doesn't seem to be how the US State Department is organized. There is a Bureau Of Near Eastern Affairs which is led by the Assistant Secretary of State for the Bureau of Near Eastern Affairs. This is not a "Director" level position though. There are National Security Council Directors, but they're different.
The Bureau of Near Eastern Affairs has an,
There is still a Deputy Assistant Secretary of State for Israeli-Palestinian Affairs, currently occupied by Andrew P Miller.
My assumption is the formal title of Seldowitz was the same as Andrew P Miller,
"Deputy Assistant Secretary of State for Israeli-Palestinian Affairs, Bureau of Near Eastern Affairs"
But because this is 20 years later, perhaps at one point there was an official "Office of Israel and Palestinian affairs".
Worked on the "Camp David Accords"? Almost certainly false.
I can find no information about Seldowitz and the Camp David Accords but they were signed in 1978. The resume of Stuart M Seldowitz shows from 1976-1980 he was getting his Bachelor of Arts, International Affairs. He went to St John's from 1980-1981 getting his law degree. It is very unlikely a college student worked on the Camp David Accords.
The Oslo Accords were signed in 1993, and Oslo II Accords in 1995. It is at least possible that Seldowitz was involved with them, as claimed by Krystal Ball. And, as Nate Eldredge pointed out in the comments, that the author may have intended to say 2000 Camp David Summit rather Camp David Accords.
From a screenshot of this video by Lowkey, we can see he was did testify as the Dayton Peace Accords Special Representative, but these had nothing to do with Palestine or Israel, and were related to ending the Bosnian War.