Talmud Torah is greater than all the other mitzvahs combined (Nefesh hachaim etc. And many other sources that say this), But how far does it go? Is one word of learning greater than keeping a full day of Shabbos? Or resisting yetzer hara for arayos ? Or is it just greater than ‘most’ mitzvos but not literally ‘all’..
The opinion of R. Joseph B. Soloveitchik is quoted by R. David Holzer:
The Rav Thinking Aloud p. 70
[DH:] What do we mean by תלמוד תורה כנגד כולם?
It is not that this mitzvah is equal to all the mitzvos, but rather that it brings the person to do all the other mitzvos. The whole purpose of the limud is that it comes to asiah, and asiah is the ikkur.