It's difficult to trust that Microsoft claimed it when you only provide a link to iota website.
Here's the quote from the Microsoft guy involved, that caused the confusion:
> We are excited to partner with IOTA foundation and proud to be associated with its new data marketplace initiative. This next generation technology will accelerate the connected, intelligent world and go beyond blockchain that will foster innovation real world solutions, applications and pilots for our customers. --Omkar Naik
The IOTA founders' statement is: "We have never stated that there was any formal partnership with Microsoft, and instead always referred to them as a participant to the marketplace."
You can link to a Twitter thread where they threaten to sue someone, but that doesn't mean anything. (If anything, it's another black mark against the IOTA team that they'd use this technique straight out of the Donald Trump playbook -- threaten to sue, then never follow through.)