Any journalist with credibility vets their sources. “Per a source” is pretty much shorthand for “Someone who we have verified works at Bungie and we believe is in a reasonable position to know this information” so even if it turns out to be false its very hard to sue because they printed what they beleived to be true at the time and did basic due diligence to check it wasnt made up bullshit. Otherwise they use much more evasive and broad language.