To be fair, the response didn't say "this whole thing for 6 months was due to overwhelming the cellular network."
A phased-rollout of OTA updates is done by pretty much every service you can think of, so I wouldn't focus on this or "bash" them about saying so. The point seemed to me to be an aside, as if saying "by the way, be patient if you hear of other people getting updated, as we do a phased rollout." That part is perfectly normal.
Bash them all you want for pushing a broken and poorly tested update, for not communicating about it, and for taking over 6 months to fix it. But I would leave this phased-rollout alone, as it is perfectly normal procedure, and the person who responded seems to have added it to be helpful and not as an excuse for the overall situation.
If you bash everything someone says, they stop listening completely.