To add further insult to this, he edited the article afterward and, I don't believe, mentioned that he changed it.
The original article said that we should sign and trade to get Horford his 5th year max but those 5th years are restricted from sign and trade deals. He changed that and removed the 5th year but kept everything else in there. So technically we'd be paying that premium in order to get Horford to sign a contract he could sign off on right now. So, no, there is zero reason to do that trade even for Horford who would be coming to a demonstrably worse team.