The only counterpoint to her quote is, at least up until that point, we'd seen Cox and D'Onofrio in other MCU projects in the MCU-proper outside of the Netflix shows.
So if they were going to already be in the MCU, recasting them at that point wouldn't have made much sense. That said, without seeing Sandrine Holt's actual performance, I'm not sure why many in the fandom had such a negative reaction to her being cast. Admire Zurer all you'd like, as she's great in the role, but Holt wasn't even given a chance before the fandom basically turned on her casting.