What exactly did you say? I'm intrigued as to what they consider is the tipping point for a lifetime ban.
(Partly out of sheer curiosity and partly so I can avoid this myself, as I also have a habit of making somewhat feisty comments, when I'm off my meds and in a bit of an obsessive rage about something.)
Similar thing happened to me after forgetting my mobile device was logged into the wrong Wi-Fi network, they permabanned two unrelated accounts as well that I used for completely different purposes. I appealed and got one back that I use to post on a gaming subreddit, but not the other that I used to post on a subreddit for a medical condition. Very strange, and irritating.
Fortunately there's the Pushshift archive, which mitigates that somewhat - replace "reddit.com" in the URL with "unddit.com" or "reveddit.com", these sites will fill in removed comments from this archive.
(Partly out of sheer curiosity and partly so I can avoid this myself, as I also have a habit of making somewhat feisty comments, when I'm off my meds and in a bit of an obsessive rage about something.)