"Shoudn't SW be able to land W/O using thrust reversers?
I thought landing performance for a Part 25 certified A/C was based on NO Thrust reverse."
Ahh, yes! However, this was a contaminated runway! Factored landing distance does not account for runway clutter. You must use ACTUAL landing distance numbers for landing on a runway with equivalent contaminate. 1/4" wet snow, 1/2" dry, or whatever your runway of choice seems to be suffering from at the time!
Bye Bye!