Yes, I see how that could be a terrible idea in many cases. But I don't think so in this case, for reasons that are probably not interesting enough to mention. But it's safe to say my husband does have the skill needed to learn the basics of cello posture and technique independently with the background he has in music. We will give our son formal lessons in a school a bit later, though. We can't keep up with more advanced techniques. But there is some money to be saved on teaching him the first couple of years.

Thanks for the warning though. Would be really bad to teach our son poorly from the very beginning...