Lagniappe

Stop worrying !
I have 'rotting' p-stems all over my property. I just whack em' down and forget about it . Last year, I only cut the leaves off the p-stem after they browned, and had some p-stems to remain green until spring. Most turned to mush in late Feb.-Mar.. Many of the smaller ones fell over at the soil line .
Many of my p-stems get the 'maggots', I leave them too. They're eating dead tissue so I figured they would clean everything up.
This year, I cut all of my p-stems low to the ground because my wife didn't want the place to look like a "telephone pole graveyard". Most have turned to mush. I'm not concerned because I know that the new leaves will grow through the center when it warms up. If the P-stem has dried up and sealed itself off in the center, the new leaves will burst out of the side....doesn't matter. In fact, if I didn't think that the old P-stems provided a little protection from frost/freeze, I would just cut them to ground level.
In my experience (and in my zone 8 climate), the p-stems are goners if they are cut into. They may survive if only the brown leaves are removed at the p-stem. Either way, the plants growing back from ground level always catch up with the ones who's p-stem I managed to save.
The same goes for indoor bananas...imo...stop chopping on them and leave em' be. They'll do their thing in due time. When you cut, you just create a new area to rot or desiccate. In most cases,as Tog Tan pointed out, it's not rot but just drying out of that area.
I'm no expert....just sharing my experiences...but I can tell you that I enjoy the hobby a great deal more now that I've learned to stop worrying and let things run their course.