Nobody here can say whether that would be compliant in the eyes of a police officer or the courts. We can make all the arguments that we want, but it won't prevent you from having your rifle taken, being arrested or having to appear before a judge, all of which costs time and money.
I would say this: even though the angle of the grip is the same as the Thordsen FRS-15 (since it was Photoshopped from one), I would much rather be making the compliance argument to an officer or a judge/jury with an FRS-15 on my rifle than what you've shown. I can show numerous historical hunting rifles, including some semi-automatics with detachable magazines (e.g.,
the current Browning BAR), that have the same (more than) century old rifle stock design that the FRS-15 utilizes (albeit stylized and skeletonized.) There is not a separate (from the stock) grip for the shooting hand, but rather the stock itself simply incorporates a curved section to make it more comfortable to hold.
While all solutions are in the "gray" area of what should be, but is not, a black-and-white law, yours is just a bit more toward that black side than I would be willing to go.
Quite honestly, after handling the FRS-15 for a bit, since we can't have collapsible stocks either (so yours would be fixed), the only advantage that I see of your solution would be that I could choose a fixed stock with a shorter length of pull for use in home defense. In combination with the required 16" barrel, the FRS-15 makes the rifle a bit long to maneuver in tight spaces. Additionally, while the FRS-15 holds very nicely in a traditional (side-to-target) rifle shooting position, it is a little long when switching to a more front-to-target shooting position. It's like being stuck with an A2 stock; great for some things, but too long for others.