This used to be a problem on [REDACTED]-community's jailbreak, so I get where you're coming from, Wolf.
However, on these servers, wardens being killed by invincible freedays is not nearly as much of a problem since the blues have the ability to select themselves as warden once the previous one has died, in which case the freeday who murdered the warden has now lost their freeday and can be killed. The round continues on. But what if there are very few players on the blue team?
Well, let's say there are 3 freeday reds and only two blues. When one freeday kills the warden, the other two freedays lose their invincibility but still technically have freedays if they never rebelled, and the last remaining blue can either go mental with 'last guard kills all' or continue the round as a warden, but this time with the ability to kill any freedays who are baiting or rebelling.
In practice it actually works out pretty well. In most rounds the freedays do not directly prevent the LR from being given unless they coordinate really well, which seems like a nice balance.
There is of course always the problem of freedays messing up rounds in other ways by for instance activating all traps on deathrun before the reds get there or trapping all the blues somewhere by bodyblocking them - something which would indeed be solved by giving the warden the power to kill freedays - but this kind of thing is against the rules anyhow. If this happens while admins are offline, well, shit, nobody would be able to stop them directly aside from just ensuring they don't get any more freedays.
'If it happens while admins are offline then the players can do nothing to stop it' is an invalid argument in this particular case anyhow, as the same thing applies to chatspam, micspam, favouring, false freerun, etc etc...
I meant to comment on more of the jailbreak-related suggestions, but they seem to have been declined or deleted already?