There's a PM at Microsoft called Sean McBreen who works with Visual Studio. Probably the same guy. He's posted his email address publicly before - smcbreen@microsoft.com (i.e. here https://github.com/Armitxes/VSCode_SQF/issues/2 )
Not sure what's about either. Like many rich-text editors, it can handle embedded images, but the attachment stuff proper is handled in the surrounding application.
My mistake - I was editing an email at the time, and looking at the editor and roving over the UI, I thought "attachments, of course!", without actually checking to see whether or not that was part of the editor or not.
For reference, the deleted comment above mine had asked if all of the companies listed in 'used and loved by' were legit (fair skepticism I reckon). After I answered they deleted their comment.
He tweeted pretty heavily previously. Was one of the small team who made @echofon. He'd reduced his tweeting, but was still using the account in other ways.