I agree with Tom. Len Savage is pretty much an expert, and as Tom mentioned, not exactly a rep for the Brady bunch. Recall that he said initially that it wasn't possible to convert an airsoft to a "real" gun, but after actually trying many different brands, finally found one that could be converted.
I think this story illustrates something we, as gun advocates, need to be careful of. Often times we dismiss anything "anti-gun" as biased, inflating the facts, or misrepresenting the truth. In this case, we need to acknowledge the possibilty and address it factually and without a lot of emotion. We need to maintain our credibility as the group that uses facts and truth to promote our viewpoint. Can you imagine what would happen to our credibility in next years legislative session if somehow this question came up (say HPD puts out an "assault weapons" bill) and we puff up our chests, loudly proclaim the claim (an airsoft can be converted to a "real" gun) is false, and nothing but hyperbole from the antigun crowd, only to have a recognized firearms expert refute our claim and endorse "theirs?"