This title is pure clickbait.

Hackers _which already hijacked Linux devices_ via some other means, use PRoot to run the code. That "makes these post-exploitation attacks platform and distribution-agnostic".

There is nothing in PRoot particularly useful for attacks -- making Linux software platform and distribution-agnostic is what basically every Linux developer out there wants, and there is a number of projects for this, including docker, appimage, flatpak and others.