So... What this article (and you) are saying is that an INTP relies more heavily on inward thinking to take action and solve outward/perceived problems?
If so, I would have to think on that a bit... INTPs are not so abstract as some thinkers (Te-oriented), who think just for the thinking. INTPs think for the thinking (which I enjoy), but also to work toward the solving of a problem: Usually a perceived one. If there isn't a problem, they will find one, for the joy of taking action to solve that problem. As an INTP, I find myself more drawn to thinking up solutions to problems and thinking through all the smaller pieces of information as those smaller sub-problems add themselves to the original. I want to solve my problem before moving onto another, and if there wasn't another, I would think up one.
It would make more sense, though, for the Te to be broader than the Ti. Take into consideration the ENTJ's propensity in leadership positions: They use their Te function to come up with solutions to numerous problems, but won't challenge another's plans until it becomes necessary (in their eyes) to do so. Then they solve the plan, put the plan into action, and carry it through perfectly, even if it means unforeseen sacrifices. The Ti thinkers (INTP, for instance) would (I think) foresee the problem with a plan, think through that problem in advance, then point out a solution to those involved. Then they'd remain flexible and searching for problems even in the midst of the actions of the plan, solving problems as quickly as they sprang up and choosing varying courses of action to reach the ultimate goal of the plan, which they'd had their eye focused on all the while, with as few sacrifices as they can manage.
So, in effect, the Ti would concentrate on carrying through the action with as little loss as possible, while the Te would concentrate on carrying out the plan at all costs. Think of the differences between a Ti and a Te in romantic situations: The Ti would see that there could be unforeseen problems in asking someone out, while the Te would think of all solutions to problems before speaking to the someone in question, solve those in their mind, then plow on ahead.
I think they're both action-based, but in different ways: The Ti continually searches for random mini-solutions while taking action to reach their goals, while the Te finds all solutions before going in and carries out those solutions, whether they work or not. That would mean that the Ti was broader-minded in the sense that he/she would be flexible to new ideas as they come, and that the Te would be inflexible and simply charge through the situation with their chosen solutions, ignoring all other problems as they spring up.
The Ti would in effect be a tad bit slower than the Te, if only because they are solving potential problems as they go along, rather than plunging into the fray no matter the costs as a Te might. So in conclusion, I agree, but I disagree: Ti is a slower and safer action-based Thinker, while Te is a quicker action-based Thinker. It doesn't mean that the Ti doesn't like to solve problems, simply that they solve them as they go along, rather than before they even go at it. It would also fit with the Scientist stereotype of the INTJ, as scientists form hypotheses and then experiment with them to discover which is the correct hypotheses, rather than INTPs (Thinkers) who experiment within the confines of their mind to find what is believed to be the correct hypotheses before experimenting in the tangible world. At which point, they could nearly always be found to be right, because they thought through all the potential problems beforehand.
I hope that vaguely made sense, and wasn't overly repetitive or long.