Jianying Ji wrote on Mon, Dec 30, 2002 07:10 AM UTC:
I think the question is essentially, if a player has a choice of
perpetual check, or a different move. Can s/he chose the perpetual check
instead of the other move. which is covered:
http://chessvariants.com/d.chess/eternal.html
So I think the answer is yes and charles's friend is probably right.