a) The author has bought way too far into the idea that everyone is equal and finds it icky
b) It's identity verification has had some problems (fixable)
c) It provides an incentive for TSA lines to stay long, similar to TurboTax
I find (c) a somewhat reasonable concern on its face, but TSA Pre already gives the same incentives, but via a government service. Other entities also have the same incentives: Airlines like the ridiculous liquid situation since it causes some people to pay for checked bags.
It's not really clear this one is any worse.
IMO people who do not like Clear should be leading a charge to fix TSA and obviate the need for things like Clear and Pre rather than railing against them since they clearly provide something that people want (to skip the line).