Llama's license does forbid it:
"Llama 3.1 materials or outputs cannot be used to improve or train any other large language models outside of the Llama family."
"Llama 3.1 materials or outputs cannot be used to improve or train any other large language models outside of the Llama family."
https://ai.meta.com/llama/license/
Section 1.b.iv
The official llama 3 repo still says this, which is a different phrasing but effectively equal in meaning to what the commenter above said.