I don't think Toonces meant that we shouldn't keep the Sabbath. I believe he was making it clear that being legalistic about keeping the Sabbath as if it was a salvation issue is wrong. I don't think that we should ever point a finger at another brother in Christ and tell them they are a dirty sinner because they don't keep the Sabbath. I believe that is something the "World Wide Church of God" has been guilty of, and one of their strong man tactics.
As much as I believe keeping all the commandments is extremely important. We don't need to beat ourselves up when we slip up right? Concerning the Sabbath day, it is a very hard commandment to keep. Especially if you are a working person struggling to make ends meet or provide for you family. Employers' in this day in age are not very forgiving, especially when it comes to religious issues and rights.