Jet A1 would soften and re-activate the old bitumen, and should stay in the mix for a few months to help it all pack down. It might be better and less soft with a mix of Jet A1 and diesel, and even add a bit of old engine oil in the brew.
The RAP however is still a little bit short on bitumen compared to fresh asphalt, which is why it is slightly friable. The bitumen emulsion adds the missing bit of bitumen.
Cheers,
OverRun