To hide columns I think you have to hide them one by one so loop over that matrix rather than select the columns.If you have JMP16+ you can use For Each, otherwise change that to "normal" for-loop
Names Default To Here(1);
dt = Open("$SAMPLE_DATA/Big Class.jmp");
col_idx = [1, 2, 3];
For Each({idx}, col_idx,
Column(dt, idx) << Hide(1);
);
From scripting index:
-Jarmo