I have not had any experience with this type of wood. However, when I was setting up my 75gal tank I found a large piece of hardwood by the edge of a lake in OH. It was not a conifer, but a hardwood. I scrubbed it down, soaked it in the tub and once it would sink in the water, I put it in my tank and used it. No bleach/soap/detergents of any kind. This has been about 7 years ago, and now it looks great. However, I too have noticed that the surface of the wood is soft. It has quite a bit of algae on it at the moment, but nothing that the algae eaters can't handle.
If it were me, I'd just scrub your piece of wood down well and use it. You may consider a few plecostomus to do the final de-algaeing before planting the tank--keep it as a fish-only tank at first until the wood has "settled in". However, I'd just go ahead and use it. My $0.02.
BTW, that's a beautifully stunning piece of wood!