I can see where a soak to get rid of insects could be useful, but beyond that I am not inclined to worry... I have never thought to treat a mount as a sterile environment, and haven't had any problems using relatively recently cut wood. Air and sunshine are fairly good disinfectants... it's just not an environment where bad micro-organisms have much chance to multiply. Maybe if I were putting them in a closed system like a terrarium I'd be more concerned.
Finally mounted with fishing line after I soaked the wood I am not sure what type of wood it is (I found it under an oak tree but who knows what it really is), but it was dense and did not have any rotting. I also mounted a Phal from my grandma instead of the sedirea japonica as it’s still in transit and I’m impatient (first time seeing a mounted Phal and it looks so much nicer than when potted). Thank you everyone for your help and insight.