Every review I have posted on Glassdoor has been with a disposable email address, using my own device and using a public WiFi hotspot. I once had an employer try to get legal on me because I went to work for a rival after they laid me off - so I know some employers can be petty like that.
I trust Glassdoor to keep their promise of not releasing my ID voluntarily, but when courts get involved all bets are off.