There is nothing sneaky about it.
And it's not an exploitation of the OGL. It's doing exactly what the OGL was designed to do.
When the original 3e team took over control of the D&D brand after TSR collapsed, one thing that they were very much concerned about was that the D&D brand might one day sit in limbo with no product support, held by a rights owner that would jealously guard a brand they weren't publishing from its fans. They wanted to ensure that whatever happened to a corporation, however a rights holder behaved, D&D would always belong to its fans and could never therefore be killed. They managed to sell to WotC management the idea of the OGL that was written basically to give D&D permanently and irrevocably to the fan community.
When 4e came out, management wanted to take the game back. They wrote a game that wasn't compatible with the OGL and wasn't released under it. Effectively, they tried to revoke the fans ownership of the game. Indeed, they even revoked the longstanding partnership with Pazio by which Pazio was effectively supporting TSR's brand and assuming a large amount of risk in printing what WoTC considered high risk/low profit IP centered supplements like modules and magazines. Pazio, which at the time was basically wholly dependent on WotC, was faced with corporate extinction.
But the OGL was designed specifically to prevent this from happening. So Pazio did exactly what the OGL was designed to do - ensure that regardless of corporate machinations, D&D would always be supported in some form - even if it was nothing more than a labor of love. But of course, Pazio quite rightfully in my opinion has thrived, producing fan-centered content that arguably more fans of the game admire and want to own than what WotC has been producing. WotC in the mean time tried to kill sacred cows, focused on mechanics over IP, tried to rewrite 30 years of canon, destroyed fan favorite intellectual property with things like the Spellplague, and spent more time creating a system for people who didn't like D&D than they did trying to develop a relationship with their existing fans. It doesn't bother me in the slightest that that didn't work out, and when 5e was announced it was announced with tremendous more humility than we saw with 4e. And surprise surprise, all that humility and due consideration for the customers' wants seems to have resulted in a system almost everyone admires, albeit it still seems too late to truly save the brand after the damage that was done to it.
But Paizo bears no blame for that. They didn't trigger the divorce.