It is fair to say judgement is allowed in any situations.
For this hand,I know Gib's double is penalty,however I have no confidence to defeat opp's 1nt,so I think it is allowed for me to respond 2♣ as weak bid so as to let pd bid its long suit.
However Gib's 2♣ explanations --- illogic and let me feel uncomfortable,what's twice rebiddable ♣? who kow its exact meanings?
Without showing weak approach,it can't be a adequate bidding system.
Then a strange thing happened after opp's 2♦ overcall.
1- Gib N should be cheapest to bid its suit holding - 2♥ instead of jump bid 4♣.
2- If Gib N really hold 2-card ♣,why pass at first after my 2♣? and 4♣ is unnecessary and illogic,even basic robot.
Above show Gib need more bidding rules here.