What an interesting discussion!
If I may return to this,
waga oya no
shinuru toki ni mo
he o kokite
Even at the time
When my father lay dying
I still kept farting
I don't think the poet is being funny, or vulgar, or overly philosophical. Now, I don't know much about the Japanese culture, and I may be wrong in my understanding.
He compares two events, one seems to be huge- a death, the other- very small. But they are not so different. We have no control over any of them. They happen independently of what we do or what we wish.
The poet does not mean disrespect to his dying father, he just had a bad meal, or he has a bad stomach. His father does not die in purpose, it's his time. We can postpone, or try our best to fix each of this events, but neither our bodily functions nor our death are our servants.

What I got from the poem is that we don't have to consider any event too big or too small. They are equally important and unimportant.
I think the poem is genius

. If I have understood it right

Best,
Vida
PS I really enjoyed all poems!