You may not be interested in the morality going down here, but if you go check some Admin hang outs you'll find a lot of people are incensed by IB's actions, including quite a number of vBers with no intention of moving to Xen. A lot of support is coming Xen's way due to what quite a few people are viewing as unethical conduct. Simply put it's been a PR shambles by IB, and it is going to come back to bite them in the bum. The winner here is Xen, so much good will has been generated with the name quickly morphing into a brand, well done IB.
Sure, you will get a lot of people who are about our age, people with longtime admin experience, and maybe folks with a decent education to see through IB's tactics.
Guess what though, IB is ok with losing your business.
They are more focused on the hordes of younger people who come to their site looking to buy vBulletin.
That is what they want to protect. They want kids who dont know what they are doing, who will buy the license for their little forum that never attracts any members.
They dont care about what people read on Admin Addicts or what have you, their core demographic is people who have never visited any of those Admin sites.
They can sell a crapload of those licenses and laugh all the way to the bank, they wont care about losing some old timers like us.
That is the corporate paradigm they operate under.
At the end of the day the "moral" argument is moot, this is a business decision for them.
And making sure that there is no active and embarrassing XenForo discussion/advertisement on their sites is a big deal.