Feeling guilty for suggesting the tree sealer. But doesn't exposing the
heart wood of a tree open it up to serious problems. Yeah, I know, logic
is only as good as its' premise but, what is the premise here?

When they've done the experiments, looks like leaving it alone really is the
best option as far as "sealing". Turns out the sealer holds in enough
moisture to let the fungi grow. Harm done by your recommendation,
most likely little. Just one of the un-needed things they're happy to
sell you. g

Kay