While I will fault Blizzard for many things with BfA, one thing they have been very clear and good on is being very specific about what applies and what doesn't. Even in this announcement it makes sure to state that it does not apply to the 8.3 factions. If it didn't apply past Exalted, they would have specified it. They would have stated very specifically that you can use the buff to get Exalted. They didn't though.
"Exalt in your buff" isn't some weird way of saying "get Exalted". To exalt is to rejoice and to revel. They are using exalt simply as a tie to the reputation system because it is the name of a rank, not specifically.
They could come back, but assuming they are saying something they didn't takes a lot more reading into something than assuming they are at face value and them clarifying later or changing their minds.
Until the buff goes into effect or a blue post clarifies, there is no reason to assume it doesn't work for paragon. You would have to make assumptions to assume it doesn't.