I don't buy the discovery rights thing, MLS has been pretty consistent in resolving that issue by forcing the rights holder to just take some GAM from the team the player wants to sign with.
He's said he wanted to come to MLS for years, I think he didn't have many options. Assuming he wanted either nice weather or a major US city, that narrows the options pretty significantly. Neither of the NY teams seem interested in signing that type of player, gotta keep those DP spots open for german second division benchwarmers.
LAFC and Miami are not looking for another DP. LAG looks to be in an off year and they may be waiting to spend until Puig comes back. Orlando isn't that far of a leap if you take all those other teams out of play. Warm weather, no state income tax, and a track record of being one of the few other teams in the league that sign aging stars like Greizeman.