I completely agree with this. Sometimes, you're counting on a hero from the dungeon, and then suddenly, it's Isra or Sir Mullich, and all your plans are ruined; the game might be lost. This shouldn't happen.
Added 1 minute ago
You're confusing things. If I'm going to get the Air book, I know what I can do with it later and what I can't. But with a hero from the dungeon, it's like a gamble.
Personally, I don't agree with God or you that it's more important to allow Isra and Vidomina (in any form) to act than to eliminate the possibility of cheating with Necromancy.
And in general, you should post your suggestions for editing the rules elsewhere! Who knows who agrees or disagrees with whom. Everyone can see that there is an oversight in the wording of the rules. Until the rules are changed, the interpretation above will apply.
Added 7 minutes ago
For example, you can dismiss all the skeletons while the Vidomina/Isra released from the dungeon levels up to level 22.