So I found the answer in case anyone else is looking for it... Diving into underlying java objects again (using the convenient findjobj function by Yair Altman):
jscroll=findjobj(mytablehandle);
jtable=jscroll.getViewport.getView;
jtable.getColumnModel().getColumn(0).setResizable(false);
jtable.getColumnModel().getColumn(1).setResizable(false);
jtable.getColumnModel().getColumn(2).setResizable(false);
...
And use a for loop if your table has variable number of columns.