KCT allows to build ships with parts that are locked or unresearched yet. It doesn't do the check with either Launch button or Build button. KCT 1.4.0.69, KSP 1.6.1
On the other hand, KRASH does do this check every time, which I think is redundant. I think it's ok to do simulation with unresearched/locked parts, or at least have an option to allow that (I set zero prices for simulations anyway).