Admiral Rajampet's nominal superiors
I must be especially dense. It never occurred to me that Rajampet was not under their control. Where is the check and balance on that idjut?
He's under their control, at least legally. He talked them into it because he convinced them it might work and they figured Filaretta could (probably) back out if it turned out the mud was too deep when he got there. Another factor that you may not be considering is that well before Filaretta can actually reach Manticore, the Manties have already begun trashing their economy courtesy of Lacoon 1 and 2. Remember when Japan suicidally attacked the US because FDR was "waging economic war" against her over her China policy? If you're the SL, with the ISLN at your command, are you going to stand by and watch a bunch of neo-barbs get away with completely gutting your economy and --- even more to the point --- devastating the government's revenue stream (since it relies so heavily on shipping duties and fees which are about to vanish like yesterday's news)? Especially if it's likely to convince the citizenry (some of whom continue to cherish this silly notion that elected officials should be making the League policy) that it can do something like that? And that you can't stop them from doing it anytime they want to? They're running the risk you described because they're already likely to go under the bus if the operation doesn't work.
It's a high-risk option, and Kolokoltzov is very anxious about it (and wishes he'd never let Rajampet talk him into it), but now that the operation has been outed to the galaxy at large (the Manties have been flooding the news channels with accounts of it ever since Beowulf fed them the information) he can't just change his mind and pretend it was never going to happen because his political prestige, as well as the League's economy, is on the line. It's an odd sort of desperation, on the one hand, undergirdded by that lingering Solly sense of invincibility on the other. It will be a disaster if we lose! On the other hand, deep down inside we don't really think we can lose.