No, unless you consider reading the world information to be metagaming. There's always going to be parts of character backgrounds that are common knowledge. Something as part of the public history of the knights as 'was one of the founders' isn't metagaming in the [i]slightest[/i]. And the post mentioned a portrait and the 'well-known' part as a secondary note. Ignoring both of them means selectively choosing canon--not a choice that leads to a world with the slightest bit of coherency.

Not to mention how much more metagaming recognising a burly stranger as a surgeon in the knights would be if character backgrounds are supposedly beyond IC knowledge.