I've never heard of this....but nothing is going to cook like tenderloin except tenderloin.
Is the shape similar? Perhaps that is why they call it 'mock'?
In my opinion, I'd cook it as you'd normally cook chuck, long and slow, and then slice it like a tenderloin.
Did you check the difference in price per pound between regular chuck, tenderloin and the mock tender? I'd be curious to see the difference in price.
I'd also like to know how it comes out.
How can we sleep while our beds are burning???