@CGO39 Unlikely. Otto may be a rank obsessive sociopath but he isn't an idiot, and he's rather sensitive to "what Kallen would think" (relatedly this is why Theresa has a degree of influence on him as a relatively successful and "high fidelity" Kallen clone that reminds him of her). Letting the Herrschers run amok on humanity would be quite counterproductive and
certainly piss Kallen off to no end; so far every canonical reference to his endgame plans indicates he intends to wipe out the Honkai the second it has served its purpose in his grand Mai Waifu resurrection scheme.
On another note, I've no idea what Kevin was smoking when he claimed there was "no risk of containement breach" here - there was no island anywhere in the vicinity of Western Europe, nevermind now within the rather compact British archipelago, that didn't have boats lined up on the shore by the dozen and routine waterborne contacts all over the place. (We may recall the date given is roughly when the Angles and Saxons were starting to poke at the eastern facade of the main island...) He'd have to actively isolate the place with a damn forcefield or something to that effect.