The electrical engineer in the house (I guess I should listen to him because he gets big bucks for doing this) tells me compressed air shouldn't be an issue for the electronic parts. It is used in industry all the time. Heaven knows I've cleaned electronic circuit boards with far worse. When I can't find a can in my hubby's electronic stuff I use the air compressor in the garage (works great on the serger mess).
I suspect that the reason many places tell people not to use the compressed air on machines is economic (theirs). The more lint clogged sensors coming in for a $100 repair the better. My dealer/repair place uses it all the time.
For my machine, I remove the needle plate and use it to blow from behind the feed dogs out the front of the bobbin casing (I have a front loader). Top loading machines might be different.