I have followed Dayton and the A10 for quite a while and have never heard anybody refer to the A10 as a P5 conference.
Is the A10 a (very) high mid major - yes, a consistent multiple bid conference - yep.
Is the atmosphere at Dayton games P5 caliber - you bet, but several of the schools in the A10 play in facilities that resemble a small high school gym.
Do you have a source for your P5 claim?
FWIW - I didn't state the A-10 is a P5 conference in basketball, I said Dayton is a "P5" team in hoops.
Source - They're ranked #14 in the most recent poll.