Screen sharing isn't mandatory. It is only used during the review. You can choose not to do the review and simple ask your expert questions without sharing your screen.
Also, we don't use the software that is mentioned in the link that you shared. We use "Glance", a program that lets us share your only the return you have open in TurboTax. We can't see anything else on your computer. Glance even blurs out some of your personal identity information, like your SIN, from the tax expert.
