That’s exactly what they say though. Ki Adi Mundi says “they’ve been extinct for a millennia,” Mace says “I don’t think they could have returned without us knowing.” They don’t get angry or anything.
I’d disagree with that. Saying that to me is different from being unsure and pondering the possibility. They kinda deny it basically more than not to me. I think it’s not a full blown denial of even the possibility as a whole, but one that I think speaks to their view of themselves and their powers regardless, more a dismissive view of it. They’re not completely blinded entirely, but that doesn’t mean they’re not arrogant to me. Like I said, being arrogant, to me, doesn’t mean they’d be utterly pompous and/or bullheaded about it.
You cut out the part where they literally told Qui Gon to investigate it further and that they’re going to help, does that count as “pondering the possibility?”