Good catch. Speculation is NOT fact!
Note the source, which the author links: "Merciful God, Merciful Church An Interview with Cardinal Walter Kasper"
"Kasper: Thats a real problem. Ive spoken to the pope himself about this, and he said he believes that 50 percent of marriages are not valid. "
https://www.commonwealmagazine.org/kasper-interview-popefrancis-vatican
Kasper is quoting the Pope. If one were to apply the reasonable man test, this reference does not qualify as "wrongful speculation", "unjust" or a "falsehood". The fact is that his close associate, Cdl. Kasper, (whom he has publicly complemented for his "serene theology" in regard to this issue) is claiming to quote Francis. The Pope has a massive PR machine at his disposal, and it is well within his power to clarify or correct any misrepresentations made in his name. Yet he has not seen fit to do so. Therefore it is unreasonable to make the charge that the reference is speculative or dismiss it as false.