Hi Millty,
the reason the PB told you that, is because when the water temp gets around 50ish degrees, its too cold for the chemical reaction in the salt cell to work. So chlorine generation ceases with a SWG.
Also, even if the SWG is working with lower water temps, algae doesnt grow very fast and teh sun generally has a lower UV in winter, so the chloring lasts a lot longer. It would be easy enough to overchlorinate the pool with a SWG if you didnt keep your eye on it.
TFP doesnt generally recommend using chlorine tablets because they also add other things to the water that may not be desireable. You need to understand how different chemicals effect your pool before you use them. Once you understand it a bit, then the tabs can be very useful on occasion.
We recommend using liquid chlorine instead of tabs in the winter when the water is too cold for the SWG to work. Liquid chlorine does not add anything other than chlorine and a tad bit of salt to the water, and its generally less costly than using tabs as a chlorine source.
There are two main designs of chlorine tab feeders. One installs into the plumbing just past the filter, or heater if you have one. The other is a floating tab despenser which floats around in the pool.
The built in tab feeders are a couple hundred dollars or so, the floating ones, which I would recommend for temporary tab chlorination once you learn the chemistry better, are very cheap.