Can I remove accumulated sawdust from fiberglass insulation?
Blow it out with compressed air instead.  Any of the modern, &quot;made safer&quot; type blow guns should be weak enough to not tear up the insulation.  (I'm thinking air off a compressor, not &quot;canned air&quot; (basically freon), the latter wouldn't be powerful enough.
Then, in the future, don't do woodwork around unfaced insulation.  I totally sympathize with not wanting to drywall, because access to utilities is a huge money saver. But at the least, staple up some 4-mil plastic sheeting and replace it every few years when it gets rotten.