Since they still don't understand the root cause of the runaway, 200 times whatever has no meaning. You can't say that this was a statistical anomaly or that we'll be seeing batteries pop every few months from now on. But it won't matter.
Safety of the modified system will surely be demonstrated by analysis, and the white paper has almost certainly already been written, by someone with an impeccable reputation, and approved by a lot of others. What can FAA say - "pants-on-fire"? "No sir, no fires around here."