SS is fine for a few weeks as an introduction.
If you are still making gains, then milk it for a few more weeks yet.
If you have plateaued, then it is worth switching to a more flexible progression setup such as 5/3/1. Considering that you also want to lose weight, the additional conditioning and volume available in several of the 5/3/1 templates will be valuable.
If you are smart about it, you ought to be able to shed some excess poundage without losing too much strength (if any). Your weights may go up a little slower, but the health benefits will likely be worth it, as 5'9" and 260 is rather bulky. I'm sure you would rather be a jacked 5'9" and 225 two years from now than hovering around 275 for the sake of an extra 30 pounds on your squat, right?
In general, I strongly recommend that you continue lifting weights. Contrary to popular belief, strength training is crucial for people trying to lose weight. Nobody wants to lose MUSCLE.