Did we get the Ginzuishou to play with for terminate Galaxia in 4000 CE project?
That depends; if Usagi and the Senshi are gone, did the ginzuishou ever appear to begin with, and if it did, is there anyone around who knows how to
use the damn thing?
Given your lack of follow up I'd say it's safe to assume that you've conceded hardware doesn't cause atrocities and those glib remarks about the Manhattan Project.
I will grant that the weapons themselves do not cause problems--a stable bomb in a locked room isn't harming anyone--the problem is that you are suggesting those weapons be used against Galaxia which will have all sorts of negative reprecussions. The Ideon, the Evas, Chise, none of the tech behind them or the weapons themselves could hurt people by themselves. The problem is that that tech is going to be
used, and it has the potential to fall into hands that will have no problem with using it against civilians, which is part of the reason why I'm not concerned about Usagi having possession of the ginzuishou; she doesn't fall into that category.
And a thought about that ballistic missile defense system you mentioned earlier;
We've seen anime Usagi take at least one blow that should've crippled or killed her; in the battle with Rubeus she was smashed against a solid steel bulkhead hard enough to crack it. Now I'm no physics major, but that kind of impact should've ended with a liquified spinal cord--at the least--or something equally crippling. Instead, Usagi seems to merely be stunned for a few moments, indicating that the girls have some
major protection against blunt trauma and physical attacks (thus my earlier concerns about 'Senshi vs Government ends with sniper fire' are unfounded unless the girls are targeted in their civilian forms).
Now consider the disparity in power between R season anime Usagi and Stars season manga Galaxia. If you apply the same rule to the manga characters and say that they have damage reduction vs physical attacks, and you say that that DR increases in proportion to their magical strength (a reasonable deduction, I think; their magical defenses certainly seem to improve over time), then those KE rounds you mentioned earlier
might give Galaxia a nasty bruise at worst.