No. Specialized-knowledge transfers under a blanket are limited to professionals, which requires a bachelor's degree or its equivalent. He can still qualify for L-1B through an individual petition, which has no degree requirement, if the knowledge is genuinely specialized.
The blanket has a rule the individual petition does not
The group's blanket approval is real and useful, but its specialized-knowledge track covers only specialized-knowledge professionals. The regulations define that person as one who has specialized knowledge and is a member of the professions, and the professions are understood through the bachelor's-degree standard used elsewhere in immigration law. A journeyman certificate, an inter-provincial seal and long experience do not convert to a degree for this purpose unless a credential evaluation finds an equivalent, which for a trade qualification is uncommon.
The parent should therefore not send him to a port of entry with Form I-129S. The individual L-1B petition asks a different question: does he have special knowledge of the company's process or an advanced level of knowledge of its procedures, and will the U.S. role use it?
A welder who qualified the company's proprietary overlay procedures and trains others on them has a strong answer, provided the file proves the process is the company's own rather than the trade's.