You can't make this assumption without seeing his strokes. Many players who struggle to generate spin are the same players who don't make contact far enough in front. You have to analyze many other components of technique in order to make a statement about whether or not they should alter their contact point. For example, two players could have solid technique, but one of the players could have a contact point drastically closer to their body in comparison to the other player. However, this isn't the only variable. The most likely explanation for this would be drastic difference in the angle of the double bend. The player with the closer contact point will have a smaller double bend angle whereas the player with the larger angle will have a farther contact point. This can be seen when comparing Nadal, Federer, and Verdasco's contact points with players such as Roddick, Ferrer, and Robredo. For each double bend angle there is a small range of technically sound contact points. When pressed for time; however, the contact point must be changed. A closer contact point gives you more time. You have a few options, but for the purpose of this conversation we will only deal with two of them. Keeping your original forehand grip or switching to continental. The natural contact point for a continental grip is much closer and further to your side, precisely why it is the natural grip for retrieving. Pressed for time, if you choose to hit with your normal forehand grip, you will have to hit closer to your body. The problem with this is that you will keep your normal double bend angle, and your technique will become unsound. In this situation most players will slow their swing-speed because if they don't the ball will sail out with barely any spin. The point is that many different contact points can pass for solid technique, but you need the rest of the components in the right place to back this up. Many players don't, and have a contact point that doesn't match their double bend angle. This is not to say having a contact point farther than optimal is any better, but I rarely see a player who has a contact point farther than optimal. You cannot tell someone that their contact point (closer to your body or farther away) doesn't make a difference. It makes a huge difference for many players. As I said earlier, many of the players who struggle to generate spin have a contact point to close to their body for their respective double bend angle.
This example doesn't help prove your point in our situation. The context is wrong, because he hits with a semi-western grip. The natural contact point of a continental forehand is much farther back than that of a semi-western forehand. The only way to hit significant topspin with a continental grip would be to hit behind yourself, or perhaps directly to your side. However, with a semi-western grip, the contact point is farther in front than most people realize. Most players don't pick up a racquet and naturally pick semi-western and make contact far enough in front. It must be taught in most cases.
I find that not hitting far enough in front is a very common problem. And a very common problem that prevents the develop of heavy topspin.
I feel like this passage is misleading. Many players make the error of starting the swing way too far under the ball; and you don't want to reinforce that. Unless you're striving to play like Nadal or Andreev, you shouldn't drop the butt of the racquet much farther than 2-4 inches under the ball. You can get plenty of spin through incorporating inactive wrist involvement, sit and lift, and many other technical changes.
However, for some players, it's important to learn the steep topspin forehand simply to get a feel for how to achieve significant topspin. But, I would never recommend the forehand described for any real use.
Edit:
Great video.