Yes. The drivers themselves are safe. And from what I can see in the current installer, they do not put adware on your system.
But before you do that, what type of printer are you using these for? OS X doesn't always automatically recognize all printers and install drivers for you. For instance, only one of the three printers I use does what I would want the Mac OS to do.
1. Epson Stylus Pro 4900. OS X doesn't see it at all until after I install the drivers available from Epson. And even then, every time I print to it, the queue tells me to install drivers so the printer will work. This while it's already printing and working perfectly fine.
2. Xerox Phaser 7500. Also not recognized until I install the drivers from Xerox. Then OS X will download updates for it.
3. Lexmark MX410de. At least OS X recognizes this one right off the bat, downloads and installs drivers for it. But the functions are limited that way. I still have to get and install the drivers from Lexmark in order to get a full feature set.
So, what type of printer do you have? Make and model. It's entirely possible the manufacturer has their own drivers you can use rather than resorting to the generic Guten drivers.