Truthfully, Bob Sutor never liked Mono. He asked about it several times before and wanted it removed [1, 2, 3]. When faced by Mono 'guards', he politely explained at the time, "I don’t want to get into the well-known controversies around Mono in this thread, but for those who decide not to use it, for any reason, it’s good to know how to avoid it."
I emailed them asking about Linux support a couple months after the Watch Instantly feature came out because I wanted to take advantage of it, and they responded saying that they were working on Linux and Mac OS support but had to work on security issues, so I stuck with it thinking that I would eventually be able to take advantage of the feature. Over a year later, there was still no Watch Instantly for Linux, so I canceled my subscription. I hope they eventually get around to it.