Agreed, anything that gets a mass up to sub-orbital hieght can probably be used as as an ICBM.

I think the slightly concerning thing here is that thus turns a small rocket in to an intercontinental one. Secondly, this is pretty legitimate civilian tech. Thirdly, if it's a cheaper launch vehicle it's a cheaper missile launcher.

You are right about the frequency of use question. One launch a day vs one launch a minute changes the dynamic of use hugely.