I linked traditionalism, not extreme sports, with Si in a post above here. I was telling Saturned that if she has inferior Si then that just means she's a non-traditionalist. The ISFP and ISTP, who are Se auxiliaries, like that kind of excitement, not necessarily extreme sports. And I know an INTJ who was into extreme mountain-climbing.
The word "stereotyping" is stupid and needs to stay in the PC realm. All typology is concerned with pure types. The description of the INTP in LifeTypes is not going to include the mixed bag that we all are. The behavior of functions in psychology is an ideal, not necessarily real.
However, I don't share your contempt for functions tests. Most people who take one already know their type. And the results I have seen more or less reflect what function theory predicts. I would not throw out a result because it does NOT justify function theory, which is all you are doing. That is a circular logical fallacy which seeks only to justify the conclusion that function theory comes from God Himself in the person of Carl Jung.
I went through my "religious" dogmatic period 25 years ago, and eventually you'll get over yours too.
So far in function test results that I've seen, the function that is supposedly the Inferior ends up at the bottom of the results, or second from it. Since I've seen a great number of results posted over time, I find there is great predictive power in that and I wouldn't ignore it. But if there is an anomalous result, as when an INTJ arrives at Ti as the highest result, then this is worth looking into and is not a result to contemptuously throw in the recycle bin.
But as always there are caveats with any test that are worth looking out for. For example,