Shielding computer moniters is the easiest thing on Earth to do. For less than five bucks you can buy a filter that makes it so that the screen is only visible from directly in front of the screen and a couple feet away. If that is too hard, simply putting computers at the right angles or using desks with dividers (like they often use on regular library desks) can do a decent job. A login/logout procedure (which really is good policy anyway) can eliminate objectionable stuff left up on screens.
My university has no anti-porn policy in labs (although in the libraries about half the computers are set aside for research only), and does all these things. There are rarely ever problems.