As I explicitly wrote, I am aware of the various shitos regarding keeping one or two days. One can “pull out” of the poskim any answer one wants, and there are heavyweights on both sides, as some of the above commenters have mentioned.
However, simple logic (surprise, the halachah and many poskim are logical) demands one day here in Israel, because here there IS only one day. All other factors are irrelevant.
I can logically accept a Brooklynite keeping two days here provided he didn’t adjust his clock upon arrival and is acting according to Brooklyn time, seven hours behind.