Sure - if that's how you define upper middle class - then by definition, it is true.
I'm not sure that's actually what the upper middle class is.
The US is >50% urban. Wealth MASSIVELY skews urban. Home values massively skew urban.
I would not be surprised if >50% of the "upper middle class" does not own an expensive SFH in the suburbs.
And, again, this is beside the point.
If income tax is reduced by 50% for the average upper middle class family, and then a LVT makes up the difference - there is no change. You're just incentivizing different behaviors.
It comes down to implementation.