Could it be that this mod does not prevent silos in manual mode from launching if they are filled with an item that is requested?
I think that's what I observed, which is why I started making my own mod, and may have now have difficulties with that same problem.
Could exchange findings/ideas if you want.

That's not actually something I've ever looked into or care much about, to be totally honest.

Usually the user could avoid loading items into the silo in the first place, but would be nice that with a launch signal, it would actually only launch with the signal.

Anyway I found that we are supposed to be able to turn off the silo's provider logistic point, which would then allow us to control it exactly via the launch rocket api, but I've actually found a serious bug there.
https://forums.factorio.com/viewtopic.php?t=133283

My goal is to, together with my radar mod, being able to build a platform by sending up the exact buildings required using mixed rockets.
https://mods.factorio.com/mod/hexcoder-radar-uplink

I'd probably need to also prevent other silos from auto-delivering somehow