Question about the Rama

Hello Sonia.
This is the language of the law:
Torah study is canceled by hearing the reading of the Megillah, much less the other mitzvot of the Torah, all of which are rejected due to the reading of the Megillah, for there is nothing for which the reading of the Megillah is rejected except for a dead person who has a mitzvah that he does not bury (for his needs), and the one who violates it is first buried and then read.
Haga: And all this is not a matter of preference except in the case of the necessity of doing both, but if it is impossible to do both, there is no mitzvah from the Torah that is rejected because of the reading of the Megillah (Ran and Y. in the name of Tosafot and from the Mizrahi Mizrahi). And if it were a mitzvah before, we would have been precisely in allowing him to read later (from the Mizrahi Mizrahi).
The Rema writes that no mitzvah from the Torah is rejected because of the reading of the Megillah, and even a dead mitzvah is like this.
You ask what he wrote at the end that implies that if he cannot read later, then reading the Megillah will postpone the mat mitzvah. But that is not the meaning of his words. What he means is that the mat mitzvah is read before the reading only if he can read later. And what if he cannot read later? Then he reads the Megillah first and then buries the dead person (meaning, in any case, one does not miss the burial of the dead person). And what if he cannot bury the dead person at all afterwards? Then of course he forgoes reading the Megillah, because reading the Megillah does not postpone any mitzvah from the Torah.