For the record, all wood "rots".
If ther wood is dense and old, it will be fine for use.
Any softer rotten parts should be cut and removed, generally anything
that you can pick off with the fingernail is too soft.

I've collected wood for nearly 25 years, never had an issue.
I do not use bleach, there is no need or issues with critters/bacteria
etc.
They leave or die once you submerge the wood for awhile.


Regards,
Tom Barr