It's hard to tell, hopefully he replaced the bracket behind the slider. If not the bracket will just bend, and I doubt the sliders would do any good then. This is just a guess from what I can see in the pic.
If he just bolted the slider to the fairing stay bracket, it (frame slider) serves absolutly no purpose. Unless modified to be stronger, which I doubt it would be songer than the frame, it would indeed just bend.
Well after my lowside out of a hairpin this weekend the Sandia track and sliding down the track on the side that those are on and where they are located...they would have done absolutly nothing. As mentioned earlier that fairing bracket stay is not strong enough.
it completely defeats the purpose if it's just on the fairing. DON'T do it.
Do it right and cut a hole in your fairing and bolt it to the engine mounts. I know it's scary and all, but I guarantee it will protect your frame much more so than just attaching to your fairing.
I had a look at the pIc then walked out and looked at my bike and tried to figure out what was the large bit of chrome fitting I can see in the pic behind the Slider, see image, and to me it looks like he has a 'New' fitting between the fairing and the frame replacing the original tin-foil one.