Sorry bro, but I completely disagree with this statement.
Orals like anavar and winstrol are known for their keepable gains. You don't
gain a ton, but what you do gain is typically lean muscle. Even orals like dbol and anadrol will produce lean muscle gains. If you keep the water retention down with adex or something along those lines, I don't see any reason why you couldn't keep a good portion of those gains.
Lean muscle is lean muscle. It doesn't go away in a matter of days like water retention.