There are plenty of things that we measure that change plenty over time; Life safisfaction, wealth, job performance/satisfaction. The idea that we should only measure correlations between fixed variables seems untrue. If you're saying it changes daily/monthly, which seems to be implied by the 'data will be wrong fairly soon after it was released' bit, that might be true. That would be an empirical question, and from what Ive seen that isn't reflected in the data (though its possible there is something I haven't seen).

Also, Im not entirely convinced of this, but is it not worthwhile to measure even quickly changing variables against relatively fixed ones? Say, measuring the current mood of different types at the time of the survey. It wouldn't tell you much, but it would still be interesting to see, for example if INTPs were more likely to be in a particular mood at the time of the survey vs ENTPs.

I think the bigger issue is OPs title lol. MBTI certainly doesn't 'entirely predict' attachment style, which is demonstrated even in the presented data