Neither the person you’re replying to nor the blog post call it open source
Open-weights means weights are released under an open-source license.
I would, contra the OSI, not consider the model to be open-source even if the weights were under an open-source license. But that is the minimum condition under which it could be considered open-weight.
But it compares itself to Qwen (Apache 2), GLM (MIT), Beam (Apache 2), Inklink (Apache 2)...
Although to be fair, Kimi contains an identical carve out.