Looking through the specs and the behaviour of webmention.io, it sure looks to me like that content we receive in a webmention is going to be either stripped text or sanitized HTML, but not Markdown. For example, the IndieWeb wiki covering displaying comments doesn't talk about rendering content this way:
Additionally, this issue as well as various examples I've come across lead me to believe webmention.io is passing sanitized HTML back.
As a result, I believe it's best to remove the code that automatically passes the webmention content through a markdown parser and instead leave that to the users, who can always do the same thing in their templates.
Looking through the specs and the behaviour of webmention.io, it sure looks to me like that content we receive in a webmention is going to be either stripped text or sanitized HTML, but not Markdown. For example, the IndieWeb wiki covering displaying comments doesn't talk about rendering content this way:
https://indieweb.org/comments#How_to_display
Additionally, this issue as well as various examples I've come across lead me to believe webmention.io is passing sanitized HTML back.
As a result, I believe it's best to remove the code that automatically passes the webmention content through a markdown parser and instead leave that to the users, who can always do the same thing in their templates.