That website isn't a "source"... it's a guy writing stuff on his website, which anyone can do lol! Where's he getting his info from? As a5cent mentions, this could still just be G-Sync 'compatible' (i.e Freesync), but there are arguments (and evidence) for both possibilities. We just won't know for sure until closer to launch. Even if full fat G-Sync is the intention though, LG could change their mind on this if they discover the monitor is going to come in crazy expensive. A Freesync version will undoubtedly be cheaper and they may see more business sense in going with that alone... we shall see. There is no denying the fact that now Nvidia supports Freesync, there is a much more level playing field between a G-Sync and Freesync monitor... yet one is still going to be far more expensive.
As to HDR, Daniel from LG has confirmed in this thread that the panel is 450nits... he's a more reliable source than that website you've quoted. If that's the case, this monitor is effectively usless for HDR content, and should be disregarded for anyone looking for this functionality.
+1 (100% agree). That part about a single model making more business sense is also super important.