-N stops ~C

Is it intentional that passing -N to avoid remote shells should stop ~C
and related ssh commands from being used to add local forwarders to an
existing connection? One wuld think ~C might even be unneccessary, with
-L and friends working directly; but they don't seem to work at all in
-N mode

Is there a great reason why (in ~C mode) -KL should not work to stop
local forwards?