I dont think it is Early Access case, i suppose game will be released on 6th June anyway, since the core gameplay is already here, and there is some balance polishing to do.
As far as preorder bonuses go beta entry is less annoying. Better than unique division or other content.
Eugene needs money for baguettes.
There will be people who spent 100h in beta, so that could be enought to be fed p with any game -> no buy.