Personally, I always found this entire thing a bit iffy, and find the concept of a fleet assault to be the least iffy part of it.
It always struck me as weird how this escalated. Smuggling the occasional team of mercenaries down to the planet and the occasional frigate or industrial's worth of survivors out through various means felt realistic. Hostile penetrations of air space always felt a bit like walking on the edge of what was acceptable, at least with haulers. That is why I am very happy that some within the Amarr where willing to play inside agent and thus provide a plausible way to save people.
But things soon escalated beyond that and several capsuleers started landing armies by the hundreds or even thousands and even set up staging areas in space, and that to me felt very weird and kind of unrealistic, since when can we invade a planet like that? If we had a fleet in orbit keeping the Khanid at bay, okay, but appearantly Kahah's airspace was just constantly being breached by entire army transports, or so it seemed with all the people claiming to land troops and bioweapons and what have you.
But people seemed happy enough to go with it, so I was happy enough to not make much of a stir, but now that a fleet's involved it's suddenly problematic?
I find the fleet to be the least questionable part, in part because the devs have shown a willingness to deploy NPC's (friggin' Concord!) to handle troublemakers in orbit, so I figured at worst maybe Chakaid will show up and summon a few dozen fleets if this was really deemed to be unrealistic and we'l be pasted the moment we enter system. And if not them, players also have a very big option to field their own fleet and make the operation a failure, there is a lot more forewarning involved here then with most "real" ops, so it seems like there are plenty of tools.
But beyond that, capsuleers seem capable of fielding pretty impressive fleets, so I find a breaching of the blockade with brute force plausible. at least for a short while.
The short while is important. No, we can't beat the Khanid navy, but we can get in, drive them off, and do our thing and get out before reinforcements arrive, hopefully. And that's only if absolutely everything goes according to plan, and is the absolute maximum that can be achieved here.