Yes, it is possible to use points at the GF. However, you would be trading out of the
DVC system to do so, and the point costs at the non-DVC resorts are much, much higher than they are at the DVC resorts. Here's an example:
To stay in a savannah view studio at AKV in the cheapest season, it's 11 points per night for Sun-Thurs, and 23 points per night for Fri-Sat nights.
To stay in a savannah view 1-bedroom savannah view villa at AKV, it's 23 points per night for Sun-Thurs, and 45 points per night for Fri-Sat. This villa includes a full kitchen, living room with a sleeper sofa, master bedroom with king bed, a jacuzzi, and a washer/dryer.
To stay in a garden view GF room, it's 41 points per night for Sun-Thurs, 74 points per night Fri-Sun. Yes, you read that right. It takes four times the points to stay at GF compared to an AKV studio, and twice as many points as it would to stay at an AKV 1-bedroom.
And...there's a $95 fee anytime you trade out of the DVC system.
Another important thing to know is that unlike point costs for DVC resorts, the cost for non-DVC resorts is NOT fixed, and pretty much goes up every year. There's no restriction on how high they can go, so down the road, you will likely find that you need to buy more points to stay the same number of nights at GF. Disney can also restrict the use of points for non-DVC options, or take it away altogether.
So....now you see why the guide was non-committal when you asked about GF.

If you plan to stay at non-DVC resorts only occasionally, it's not a bad thing. But, if you would want to use your points to stay at non-DVC resorts on a regular basis.....DVC would be a very poor value and probably isn't for you.
ETA: If you wanted to stay at DVC resorts, say, every other year, alternating with the GF, you could also buy only enough points to cover your DVC trips. With the use of banking and borrowing, if you bought 50 points, you could take a 100 point trip every other year, or a 150 point trip every three years.