When LazyWizard was working on the server calls for bitbucket some workarounds were exploitable and Alex asked him to not bypass his security so those stopped there is still some Java exploits but that is legacy code issues and not LazyWizard's fault. Different reason from guys like Vayra. Source: Dude, trust me bro.
Here is what I can find about your PC collected by a game and sent through a server call:
-window size and names of each window, including windows running in the background and not shown on screen
-read what is on the clipboard and where it came from
-read any files anywhere, even those not included in the directory
None of these things needs admin privileges and can even be incorporated into the game itself when using data to affect game mechanics.