Hope this does not count as necroposting, but it didn't seem that the dilemma was solved.
I ran into the exact same problem just now, had a great game with tons of a support thanks to going through the Locomotivus and Crew Reclamation Facility.
Initially, I was thinking of just counting until I get to 10 genestealers killed and that would be it, but I do not think that this is correct. Keeping in mind that killing all genestealers in the formation and having both blip piles empty qualifies as a win condition, I think that it simply remains the only valid win condition.
The following situation probably clarifies why. I believe that the intention of the location is to give you a chance if you're doing bad, low on support tokens, so you can just kill 10 genestealers and you don't have to go through the minimum of 24(if you entered the room with no genestealers). However, if you did have a lot of support tokens on your marines it will most likely act as a support drain and make it harder now. Every time you drop a support token you risk having that support token be used on the Librarium Vault, if you kill genestealers before playing support cards to place them back on your marines.
This is usually irrelevant, if you have so many support tokens on you that you cannot place them on the card you will probably win the game either way. However, I believe you need to play until you get 10 tokens on the Librarium Vault card by freeing up tokens and then killing genestealers or by simply killing all the available genestealers.