The image went viral as protests over the Israel-Hamas war rattled college campuses around the country last spring: two dozen or so fraternity members at the University of North Carolina at Chapel Hill shielding a wrinkled American flag from pro-Palestinian protesters who had already taken it down once.

Republicans, including former President Donald J. Trump, were quick to highlight the episode in speeches and videos. But a GoFundMe campaign created for the fraternity brothers captured the most attention. Its organizer, John Noonan, who has worked for a number of Republicans in Washington, wrote on the GoFundMe page that “commie losers” had invaded college campuses and that the U.N.C. “Brohemians” had protected the flag from an “unwashed Marxist horde.”

So, Mr. Noonan said, he needed America’s help to “throw ’em a rager.”

In less than a week, he raised $515,492. A moment of heated emotions over the war in Gaza had become the impetus for a giant party that Mr. Noonan said would feature beer, country music and Greek organizations.

The party, which Mr. Noonan is calling “Flagstock,” is scheduled for Labor Day — the location has not been disclosed because of security concerns — and will feature musical guests closely aligned with Mr. Trump. But despite all the pomp, it has prompted frustrations on the Chapel Hill campus, most notably from many of the fraternity brothers who surrounded the flag on the school’s quadrangle that day in April.

In interviews, several members of the U.N.C. chapter of Alpha Epsilon Pi, a Jewish fraternity, said they were disappointed that the money raised on their behalf was paying for a party. They said they would rather that a significant portion of the money go to a charity that supports Jewish organizations or relief efforts in Gaza.

The “rager,” they said, felt callous given that it grew out of a painful moment for both Jews and Palestinians — all as the war in the Middle East continued.