if Danzo didn't have 30 men to back him up against Shisui, then Shisui would've won that fight with his next move...
Danzo was even trapped in a *NORMAL GENJUTSU* LOL... dat Sakura level...
no wait... even Sakura can release a normal genjutsu without wasting Izanagi
Kotoamatsukami would've 1 shot Danzo... and then Shisui could've asked for his eye back...
and since Danzo probably didn't have no more Sharingans on his arm yet(?) BUT IF HE DID... i don't even think that izanagi works against kotoamatsukami... but even if it did... Danzo's destiny would've already been changed.
Danzo + 30 guards is a bit too much tough... hence that Kotoamatsukami has a cooldown which is even longer than 1 day with hashirama cells