I don't use Space Age. I changed my local copy of this mod to do this and it appears to work with Space Age disabled. Mostly.
Would also like to disable or hide basic guns, rifles and all ammo. (Need to keep rocket launcher for another mod that uses it to launch seeds. BioIndustries Mod)
It also appears that Military Science 1 is not hidden.

Example code to hide pistol and ammo:
data.raw.recipe["pistol"] = nil
data.raw["gun"]["pistol"].flags = { "hidden" }

data.raw.recipe["firearm-magazine"] = nil
data.raw["ammo"]["firearm-magazine"].flags = { "hidden" }

Hi, thanks for the feedback!
I was already considering making the mod compatible with non-Space-Age runs, just haven't found the time and motivation yet. Now I have an external motivation! :) Maybe I'll implement it this weekend ^^