its not they are not going . they cant. since in their minds its impossible to activate.  saying wont lend its just to hide the facts.

mc later convince them that can be activated and goes for  the sister and the harem. and  for activate it its another comedy but become the insignia ship of the kingdom. with obvious olivia and angie on it. while MC gathers his army of plebians he lent ships. and gaves temporary command of Partner to his father in the war.  in that exact moment. that father FINALLY GROW A PAIR and by knowing was the slave of the idiot sister who framed lion..  he behead him outside the ship on same time he piss himself to zola and abandon her and their bastard childs.since those girls were demanding escape instead of fight

Actually it's quite reasonable. The people who wanted MC executed were all being "recorded" during his imprisonment because they are all going to be executed as traitors to the kingdom for colluding with the enemy. That's why MC was imprisoned for so long under Mylene's allies (basically the good guys). Otherwise, MC would've gone free but nobody knows when an assassin suddenly just stabs him while he walks outside freely. That meeting room contained only people whom MC could trust. MC knew about the imprisonment being an entrapment Op as well.

As for the Royal Ship. They pretty much explained why they can't lend it. It "chooses" the people that can activate it, and despite trying already, the King and Queen Mylene can't activate it. The Saintess is also exposed earlier for being a fake so there's zero hope she can activate that thing. The people in that room aside from MC know that the ship activates only with "true love" and seeing as they know Marie is a social-climbing money-hungry lying woman, they know the Prince and Marie's "love" isn't going to work. That ship has also only been activated by couple from the bloodline of the Royal family (whom are apparently descendants of the first Saintess and her loyal companion adventurers). It's not like they don't want to. It's that it's rationally not possible judging by the present situation.

@kamikaze00007 TY for explanation!