Unscrew broken fan screw

While trying to open my MacBook Pro Mid 2009 2.26 GHz one of the three screws that keep the fans in place broke up. The only solution to get it out now is doing a cut on the head of the screw and then removing it with a normal flathead screwdriver, but I fear that part of the iron dust that the cutting would create might end up stuck in the motherboard, causing some bad shortage when powering up again the MacBook after having reassembled it.

I have an iFixit dust blower but I am not sure it would be able to completely clean the iron dust off the board. Would it be too much of a risk cutting that specific screw? Is there any other alternative solution to remove it?