Guess the service advisor forgot to tell you that the metal filings will have to pass through the compressor first before reaching the R/D. And that your ND compressor is not equipped with a low side filter.
If the filings are in the evaporator's high pressure supply side, then they will pass through the evaporator, exit on the low pressure discharge side, pass through the expansion valve and then straight to the compressor. Some particles may stick in the rubber lumen of the suction manifold hose, only to be released at a latter date.
If the filings are in the evaporator's low side discharge pipe, then its through the expansion valve and straight to the compressor.
Odds are the filings will never make it to the R/D. But they will trash your compressor.
Flush. And don't forget to correct your refrigerant oil level afterwards - include both oil that is removed from the evaporator by the flush and any that may have been lost during the period of your refrigerant leak. And if the R/D has never been replaced, consider doing so. The car is 12 years old; a new R/D is warranted.