I doubt that Pacquiao will accept this offer. He has a limited time remaining on his career so it's common that he will pick a better opponent with a good profit return for him. Spence and Crawford is a strong fighter and at the same time has a high viewers expectancy. I believe he will choose between them since he has nothing to prove for fighting not so hot fighter.
OT, I thought Mcgregor is the one who he will fight this year though. IRC.
I also have Spence or Crawford in my mind as Pacquiao's next possible opponent. But If these both figthers would not come to an agreement against Pacquiao, Mikey is one of the best option. He isn't a bad fighter though.
I mean the fight could be entertaining as Mikey is an aggressive fighter and that's what Pacquiao wants as long as he have enough stamina left in his tank even with his age.
Let's see If they'll push this match. They might be testing the waters for now. If it really sells, they'll pursue it for sure.