All timbers could theoretically spalt due to the nature of their structure. Whether it is an attractive feature, and that does not only mean good looking , or not is a different thing.
Softwood with a blue sap stain, although still structurally sound, was not deemed to be suitable for good quality joinery so it was rejected. There has always been a certain amount of reluctance, within the building industry, to introduce any type of fungus, alive or dead, into a building. The same applies to wood that has been infested with boring beetle.
Care should be taken to ensure that any type of disease or infestation is not passed around the country. We used to bleach blue sap stain under pressure to kill off any spores.
Regards
John BHT