The 850/70 series turbo engines don't have a flame trap. The normally
aspirated engine do and it is near the throttle body. I assume
the 6 cylinder turbo engine is the same and you don't have a flame
trap.

I wouldn't cut anything around the MAF. It is a very sensitive part.
Plus, the turbo sucks in all the air the engine can handle. A
plastic grid won't limit air flow -- if it did the turbos couldn't
build full boost (and they easily do).

A MAF works by passing current through a wire. The air flow over the
wire cools it changing the wires electrical resistance. This is used to
measure the air flow and meter the fuel. It is possible the screen is
there to break up the air flow a bit to improve the ability to meter
the air that is flowing past. Maybe it helps at low air flow for better
throttle respnse or maybe it helps at high air flow -- I don't know
enough about fluid dynamics to guess past that.