A soft material like air filter flocking would most likely pass through without harm. Oem filters are worth every penny. Stihl and Husqvarna spend untold millions on research and developement on their filters. An aftermarket filter like an 028's that have the choke mechanism built into the air filter are in my experiences total junk.
I have tried aftermarket concrete cutoff saw air and fuel filters. They may look just the same as an Oem, but that's about as far as it goes. Dirt and concrete dust go right through the air filter media.
Tests have proven that the air filters in the newer Oem Stihl TS420, 500I, 700 & 800 actually work better the dirtier they get. I have seen this first hand. Some Oem filters I have seen have weighed a couple pounds when the saws come In for service.
They have been designed with over sized filters and have compensators in the carburetors that insure the power stays the same whether the filter is new or dirty, with exception to the TS500i, which is fuel injected and compensates through it's engine management system.
Once It reaches a certain point, the saw will noticeably lose power, In which time you replace it. Blowing these filters out with compressed air has been proven by extensive testing to allow contaminents to pass through perforations caused by the blowing them out.
This is what an AM air filter didn't stop in one week in a concrete saw!