The author has a point, and I think the "free as in freedom" comments are clearly missing that point. But I wouldn't say it is explained very clearly. It's framed as an attack on what appears to be a straw man. Finding a frame of reference to interpret the tirade is hard[1], and the point about the costs of work must be extracted from the rest.

[1] Hard to do well. It's pretty easy to make vague assumptions and proceed from there.