Is it mold or not? Hard to tell but parts of it in the image look “webby”.
Some info on mold in processed tobacco.
If you see mold on the surface the tobacco the mycelia probably extend through much more of the tin unseen so you can’t reliably discard only the moldy parts. Also, microwaves are a type of non-ionizing radiation and only damage mold and spores by heating them to a high enough temperature for long enough. Long enough that the tobacco would likely be ruined. There’s also the possibility that the mold is a type that produces mycotoxins. If present these toxins are very unlikely to be denatured by a brief microwaving and modest temperatures.
Molds are everywhere and we have no practical way as hobbyists to identify the species on our tobacco and determine its risk to us. The most common mold on processed tobacco is Aspergillus Fumigatus. Over 30 other Aspergillus strains have been found in processed tobacco (Papavassiliou, et al, 1971). Some Aspergillus strains produce aflatoxins which can be fatal or produce long term damage when inhaled. If we don’t know what kind of mold we have we have no way to assess the risk.
A 1968 study done by scientists at the British American Tobacco Company (Wood, et al) determined that viable mold spores from contaminated tobacco enter the smoke stream in sufficient quantities to “...warrant some consideration of the role which micro-organisms may play with regard to smoke toxicity.” Theses studies were on cigarettes which are intentionally inhaled but we still unintentionally inhale some smoke even when smoking a pipe.
There are many who have reported brushing mold off of a blend and smoking it with no ill effects. Personally, I discard a moldy tin whether it smells or not. Life’s too short to smoke moldy tobacco. Tobacco is cheap and the risk, even if small, isn’t worth it to me.
We’re all adults and can make our own decisions but they should be informed decisions.