I think that people who have symptomatic Tarlov cysts should get exercise to a certain extent. Because if you do nothing but sit, or lie around the house, then your body will deteriorate in a way. It goes back to the old saying, "if you don't use it you will lose it". I believe that you should do what is comfortable for you, and only you know what that is. If you have a symptomatic Tarlov cyst, then you shouldn't do anything that will cause you to have more pain.
When it comes to Tarlov cysts, even after you have had a proper surgery to treat, or as I like to say drain and contain, the cyst, the old saying "NO PAIN, NO GAIN" doesn't come into play. Because with Tarlov cysts, the pain means that, before surgery you are causing more damage to surrounding nerves, and after surgery you are irritating the damaged nerves, and the more that you irritate them the longer it will take them to heal. I would recommend that a person with a symptomatic Tarlov cyst try to walk each day, to their comfort level, and always remember when you are walking, that if you are walking, say to a certain point from your home and back, that however far away you walk, that is the same distance that you have to walk back. So be aware of how much distance you can walk comfortably, and make sure that you don't go too far that it will cause you pain trying to get home. And always, if possible, take a cell phone with you, just in case you need to call for someone to come and pick you up, and drive you back.