If that wasn't a big deal then why you posted, Oh, it's on sale, I am not giving any cent to begin with? You are just simply exaggerating it. If you don't like to buy it then don't as simple as that. Stop saying the things which you mean and then imply it's not big deal or that's not what I mean.
Nowhere in the terms while you purchased the software it was mentioned Xenforo is entitled to give you updates every year or insight on what's happening. If Microsoft, Apple or other companies doesn't give you update on their next OS release do you go nuts on them saying oh I want update, tell me what's happening? No, I don't think so. So what's make Xenforo so different. At the end of the day it's just a company like other companies which sells software.
Off course you'r entitled to your opinion like everyone is but please stop acting like a kid that Xenforo cheated you and you lost trust and all. You paid for current release and they delivered it. They even extended 1 yr license for many users as a good gesture because of the lawsuit.