I did not find any mention of the it being rescheduled or moved in that article. This is all it has on the location and scheduling.

Gaster arrived on site at the festival event at approximately 5:30 a.m. on Saturday, with the party — which had started the night prior — meant to go until approximately 5 p.m. Saturday evening. An offshoot of the Paralello Universo festival brand started in Brazil nearly 20 years ago; the Israel event was called Supernova Sukkot Gathering after the Jewish holiday and was hosting several thousand attendees in a rural location near the Gaza Strip, with a lineup focused on the electronic psytrance genre.

Everything else is just a hero tale for Gaster.