Then it's not a tax cut for the middle class. You have it phasing entirely out right around the median income, so someone at the median gets approximately nothing.
You could do the same thing higher up, e.g. drop the 10% bracket to zero and compensate by raising the rates for the brackets that start at the median income rather than ending there, but then it's a much larger reduction in revenue specifically because the middle class gets it too.
If you really wanted a (more affordable) tax cut specifically for the middle class, you could cut the rate between the 25th and 50th percentiles to 10% (rather than setting the existing 10% rate to zero) and compensate by raising the rate between the 50th and 75th percentiles. That would be an actual tax cut for the middle class.
The claim I was responding to—as should be obvious since I quoted it—had nothing to do with the middle class:
>> With any tax cut, the rich will benefit the most because they pay most of the taxes.
But you can do a similar thing to target any income group you want, while excluding any you don't.
Drop the 10% bracket to zero, increase the 12% bracket to, what, 15.25%. And you get a tax cut for everyone whose income is entirely in the 10% and (except at the exact top dollar amount of the bracket) 12% brackets, and no one else sees a change.