I have three Robusta that are 2', 2' & 1 1/2' trunk.
One 2' is the one I have outside protected. As far as I can tell. It is doing good, but I never can tell as it is wrapped.
So the other two are inside in the basement. The 1 1/2' is doing fine. No growth, but the existing growth is still good.
However the spear just pulled on the 2' insider. Will there be hope for this in a couple weeks?????
Was it outside in a cold rain before you brought it in, and maybe freeze? I don't understand why that size a W. Robusta spear would rot.
If you can, wash it out good. If you have a pressure nozzle on a hose that you can wash it out with, that would work. Do the best you can with whatever you have on hand. Then pour some Hydrogen Peroxide down the hole & hook up a small fan to keep that part dry. Hopefully it'll grow a new one in a few weeks if it's warm enough. They're pretty tough palms.
I wish you luck with it.
If palms won't grow there,
and you don't try,
They won't grow there.
BUT THEY GROW FOR ME :)