There's a good chance the people who arranged the meeting and the people who canceled the meeting rarely ever speak to each other.
Stallman has definitely been a massive driving force behind many of the technological developments and philosophies that back the thriving open source ecosystem we have today.
On the other hand, he has also stated some pretty controversial opinions regarding children and sexual relationships that I remember reading and disagreeing with in context.
If the tech folks arrange a nice meeting with the guy to discuss open source/GNU/etc. and the PR people are only informed later (after the first complaints of his haters undoubtably came in), the cancelation may have come to a surprise to those who set up the meeting.
It can be easy for technically minded people to brush aside politics and old statements when one wants to focus on discussions around technology, but it can also be easy to forget that most engineers and philosophers don't exist in a vacuum.
The text itself very much reads like "we wanted an in-depth discussion about open source but the organisation decided inviting Stallman was not such a good idea". Perhaps the people who invited him were naive, but I too learned about the controversies surrounding the man years later than many others.
The committee that decided to retract the invitation has clearly not done their homework when they approved the invitation, or lacks the necessary vetting procedures for guests. This is a mistake on the side of the people that canceled the invitation, but I wouldn't necessarily throw the people who sent the invitation in the frost place under the bus.