That's just wrong.

Maybe they could have bypassed the ballast and directly wired the lamp socket.

If its 120V reactor OCV is 120V and I've tested this, its not bad for the ballast, actually having a cycling lamp would be worse cause the ignitor would wear out

The only thing is that you can't install a higher wattage than what the ballast is rated for. So if it's a 150W HPS ballast, the maximum incandescent wattage you can use with the ballast connected is 150.

I think that putting an incandescent on an HID ballast requires a different calculation. The wattage of incandescent is calculated with 120v across the lamp but the ballast in this case would be designed for either 55v or 100v. Even a MH with 300Voc would probably operate the right size 120v incandescent if the wattage was proper to pull down the working voltage to 120.

I've seen things like this before too! What if it fails and the ignitor causes an arc inside the bulb? Dave Silverliner shared an instance where that had happened, although IIRC it was 70w PSMH, not HPS...

I've installed CFLs in HID fixtures with failed ballasts, and wired direct to 120v.