He was definitely against the encryption-over-SMS feature of TextSecure as Android and smartphones more broadly grew in marketshare. He also wrote the blog post on how it doesn't matter if you have multiple messaging apps (or federation between them) because the notification area of your phone is the modern federation engine. I may be paraphrasing a bit heavily but the post is at [1].
I agree I can see him being at least OK with removing SMS but it seems at odds with what I felt was his overall view of "get the most people the most security we can" and by extension increasing the number of people using secure messaging services to normalize it so simply using encryption isn't seen as an outlier. The latter part is closer to moot now more than ever before with WhatsApp being E2E by default and Apple having huge marketshare in some markets with iMessage.