Geert,
You really are giving this guy too much credit. Do you not realize that taking FOUR SECONDS to give a short update on the timing (after blowing through the 2 weeks he promised a month ago) is a pretty reasonable request? And the idea that he shouldn't have to respond because "he needs to focus on manufacturing gimbals"... that's obviously not working since he ISN'T MANUFACTURING & SHIPPING GIMBALS. It literally just takes a few seconds to say, "Hey customers, we are hitting a few snags, hopefully be shipping next week" or something like that.. Its so easy and will calm all of the "impatience" as you describe.
And one last point.. When a small, niche start-up in the tech field, with a history of problems, completely goes off the map and doesn't respond to customers, stops shipping products, and stops refunding money to cancelled orders for a couple of weeks..... those actually ARE signs that could be interpreted as a "going-concern" (AKA going out of business). Not saying they are, but saying the signs presented wouldn't make that assumption unreasonable my any means, and the fact that you scoff at those who ask that question is ridiculous.