What you're saying isn't possible, an eggdrop bot can't stop a ban from being removed from an IRC network channel, it can only reset the removed ban straight after it has been removed, and only if that ban has been set as a sticky ban - (obviously the ban could only be removed in the first place by someone with op/halfop privileges anyway). Your bot also needs a minimum of halfop status in the channel to perform that action. See your eggdrop documentation for help on sticky bans. Sticky bans are a built-in eggdrop feature which doesn't require a script.
You could however make your eggdrop bot post a message to the channel if one of its sticky bans has been removed by someone other than the owner of the bot and possibly punish the user for doing so, but that would definitely require a script. Doubtful someone will write one though.