Apparently, it's also possible to do this with a simple command line. Leaving the other guide for reference and incase people want to use it to undo their previous efforts.

Simply right click on the Arkham Knight in your game library and click Properties. Then, under the general tab, click Set Launch Options. In the box that appears add the text "-nologo" (minus the quotes of course). Then hit okay. Your game will, again just go straight to the press start screen.

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OLD METHOD PRESERVED FOR POSTERITY:
Go to Batman: Arkham Knight folder and find in there the "Movies" folder
e.g. C:\Program Files (x86)\Steam\steamapps\common\Batman Arkham Knight\BMGame\Movies

Once in there, look for "Intro_BM3Logo_fire.usm" and "nv_logo.usm" and rename them to something else. Personally, I renamed them to "Intro_BM3Logo_fireOLD.usm" and "nv_logoOLD.usm" to make it easy to find and restore them again for any reason.

And thats it, your game should now boot straight into the press start screen. :)