His claim? Bethesda has attained the rights to make and publish a S.T.A.L.K.E.R. game. However, the company has no claims to the extended universe as GSC owner Sergei Grigorovich has apparently not sold the brand.
Wait a minute, you might be thinking, so what if some blogger is making a claim about Bethesda? What is his source? Unfortunately, the only thing he says (according to Google Translate) regarding a source is “a very reliable source, whom I trust.” However, this same blogger seems to know his stuff about S.T.A.L.K.E.R. as he was the first to report about the troubles surrounding S.T.A.L.K.E.R. 2, which has since been reborn in the form of Survarium.
When contacted, Bethesda had no comment on the rumor.