Because Blender is a tool for making art and Anthropic makes tools for stealing art
Anthropic hasn't even shipped an image or video model. What is "stealing art", the fact that AI models are trained on data? What constitutes stealing in that?
Art is very varied, its not just paintings or photographs. Video games can be art, music can be art (artists!), an eloquent dance can be art.
However I wouldn't call AI training on text in books "stealing art"