This reminds me of a fund back in the 90's, you give them $XXX of stock as collateral for a cheap loan. Years later you would pay back the loan and they'd return your stocks, and of course you also get whatever gains the stocks had over the years.
Turned out it was a scam, they immediately sold the stocks you gave them.

The IRA was not amused and said, "Oh, no, you (your agent) sold the stocks and therefore you are responsible for the capital gains tax. Which you did not declare on the long past 1040, so now you owe the tax plus interest plus penalties.

I don't think Cambria is doing a scam here, but I could well see the IRS deciding that it WAS a taxable event.

As I read it, this TAX ETF is going to just hold the stocks that are put into it. That seems, um, suboptimal. Who is deciding what the ETF is going to be invested in? Anybody? If/when the ETF sells a stock, doesn't that cause the capital gain to be realized?

At any rate, you are eventually going to have to pay the capgain tax, so at best you are just delaying it.