Based on Not allowing one's tzitzis to show in a cemetary according to the Rambam and Are all mitzvos forbidden near a grave? If not, why not? If yes, why not say so?, we find that wearing Tzitzis in a cemetery mocks the dead who can't perform Mitzvos anymore (even by women Tzitzis showing in the presence of a dead woman?). However, even by tucking in the Tzitzis, it would seem that one is still performing a Mitzvah, albeit privately.
If the dead can still see the Mitzvah being performed, then how does tucking it in help? And if they can't see it being performed, then why tuck the Tzitzis in?
In other words, the dead should be able to see the Mitzvah being done anyways (think of X-Ray vision within their 4 Amos), in which case tucking in Tzitzis shouldn't help. And if they can't see it tucked in, then they shouldn't see it either way (they're covered in earth).
Or do we say that due to Kavod HaBriyos, we don't make the person take their Tzitzis off in public (https://judaism.stackexchange.com/a/37793/17591)?