The stock Android browser shows an edit link for comments. The Firefox version doesn't.
(Somewhat related, the edit box in the Android browser is reallllly tiny.)
Firefox mobile isn't really supported, it's market share is too low (I just checked, we've seen it from less than 5k clients in the last 48 hours) and doesn't ship as the built in browser on any major devices.
If this were a big break (couldn't view questions, or similar) then we'd fix it, but comment editing is too minor.