The first is ridiculous. That's exactly why it exists, to allow people who are willing and able to pay to skip the line.

 The second reason is more interesting. Basically they are arguing that one can get Clear without the same level of background scrutiny that is required to get a TSA pre check.  The attached article gives a couple of examples where this has been an issue, but at least one of them looks to me to be a TSA issue because it cites an instance of someone bringing ammo through security-which is something that is the responsibility of TSA to check at the x-ray, not Clear at their credential check.

Perhaps the real reason is third potential, that a union that represents TSA workers is being the idea of closing TSA down.

 Whatever it is, it's silly CA stuff.