I'm pretty sure this is going to piss off both HP (for showing their logo clearly) and Apple and this is probably not going to last.
There are plenty of "hackintosh" guides out there, anyone who's capable of installing OSX on a non-Apple device has probably better hardware options out there.
And considering that this will never come with a pre-installed OS you aren't saving yourself any trouble buy buying it from them rather than buying the same hardware or newer from any other source.
My wife and I both use OSX, Clover 2560ps. I wouldn't claim they're "fully functional" - The video on them is not the best. Lots of bugs in iMovie and sometimes when running 1080p video you get vertical lines on screen, and not contained to the video itself.
Perhaps the guy running this site has solved that issue, but AFAIK I have the best running methods I could find from various Hackintosh communities and guides for the model I use.
https://www.amazon.com/HP-EliteBook-8460p-XU057UT-Notebook/d...
https://www.amazon.com/HP-Elitebook-2560P-Notebook-Refurbish...
But overall it doesn't matter they are selling 100-200$ refurbished parts for 100% or higher markup with no OSX installed, so overall it's a pretty scam ;)
If you sold me a hat with the agreement that I can only wear it on weekends, could you request a takedown of my website with a video of me wearing it on a Tuesday?
Don't think I've seen a funnier analogy for EULAs
So I guess it doesn't come with the actual OS, you'll have to download and install it separately.
Case in point: Psystar [0]