Hmmmmmm. It might work, but the single point of contact (frame tube) makes me wonder about efficacy.
Motocheez welded a plate go his frame (welding makes sense to me here)
I went a different route and got some CRF50 brace plates.
The top hole uses the rear motor mount, but the 2nd hole needs to be drilled and the sleeved bolt employed. Both the welded method and the CRF50 mount form "triangles" of support. The mount shown above would act like more of a hinge I would think?
That said, it would certainly be a lot easier to install compared to welding or drilling. Let us know if you get it and how it works. Even if it just shifts the common bolt break point from the rear to top motor mount, that one is certainly much easier to replace.