OC: to clarify: the Foxes made the mistake already in declaring what they would field anyway in their first message. Normally the aggressor comes, states what he wants and what he has at his disposal. Then the defender states what he is fielding, then the aggressor can start internal bidding, or in this case, matching the defender.
So, the Hellions could have bid just some aero Clusters if you had told them your forces available (not engaging). Then you could have chosen an appropriate warship (or another answer).
(If the attacker would bid way too much (like for example, 3 Warships would defend and you still took all your ships you brought), that would have consequences for them in form of frown, scorn or even other retaliation in the Grand Council or by other Clans, Players here and almost everywhere are way too lazy, limited in time or else to play that out for realzies, myself included)
However, for prizes this big, it is not unheard of for defenders to bid everything they have, because losing their cache could prove a major weakening. Not just for the Clan itself but in the eyes of other Clans. This is just a major escalation of things to challenge for.
My 0.02 Kerenskys.