I don't see how if you cut the U-lock, you can't then just remove the entire bike easily.

Other than directly attacking the U-Lock, it looks like you could cut/remove the seatpost, remove the rear wheel and keep the front wheel & frame.

Furthermore, the front shields are virtually guaranteed to be inadequate for some users. To fit close enough to the fork, you have to design around a particular bike. Anything that fits a front suspension 2+" MTB fork will be far to wide to protect a narrow fork road bike, and vice versa.