[GAMEPLAY] Why can Rumble cast his Harpoon while overheated?? Why is this intended??

I saw this note in the bugfixes section of the patchnotes: "rumble can now correctly cast Electro Harpoon while overheated". Why? Why is this intentional behavior? Harpoon is no longer a "cast once, get a free shot" ability, it was changed to be an ammo system like Velkoz or Corki. The ability to cast the second shot if the first one triggered overheating made sense with the old style (Riven-style), because casting it twice WAS just one ability, and thats how it DID work. But not with the new style, where each cast is its own distinct ability. Did whoever made this patch simply forget that the Harpoon was changed to an ammo system?

If this isn't a hilarious oversight, then why isn't this mentioned in-game at all?