Because it will make it more expensive for people or groups of people to run open source models to do work on their own hardware. You would be taxing people or groups of people to run a program on the computers they own. This is contrary to the principles of the free and open source software movements.

This is what he says:

> I believe we should tax AI tokens and robots. Right now, if you’re an employer and you hire someone, you pay payroll taxes on their earnings. But if you buy a robot, you can usually write it off right away as a business expense. The tax system nudges you toward replacing people with machines.

A tax would slow the rush away from human labor a little and raise money for retraining and a stronger safety net. It would need to be targeted so it does not slow down the purely beneficial uses of AI, like making medicine and education cheaper.

Note the part about it being targeted. Clearly this is in the context of moderating the displacement of human labor by employers rather than a flat "TAX ALL THE TOKENS!" approach.