I'm not sure about that statement. The ridiculous list of banned weapons appears in Chapter 269 Section 10(b), however another part of section 10 reads "No person having in effect a license to carry firearms for any purpose, issued under section one hundred and thirty-one or section one hundred and thirty-one F of chapter one hundred and forty shall be deemed to be in violation of this section."
Two paragraphs later, a subsection is mentioned.
However........
Section 10 also bans machine guns. In particular, Section 10(c).
BTW, I have a client who had a LTC and is charged under 10(b). I'll let you know if the judge agrees with my reading.