That's a rule that has served us in pretty good stead.
It's not just the moral issue (though I do have dealbreaking moral problems with doing the kind of work I do for the USG) but also that the market for GSA-style services is so different than the regular market; not only is it harder and weirder to address as a market, but also succeeding there doesn't teach you much about how to make your offerings work in the real market.
(I've worked, earlier in my career, on somewhat large-scale projects [not in vuln research] serving government agencies, but have never been a principal at a company that targeted government sales, so, grain of salt or whatever).
