No, it doesn't this happens all the time. Wannstedt got the same extension right before he was fired as well (his may have been 2 years, I think). Its to put on the "you're not a lame duck coach" face, to motivate him and pretend like he's your guy. Contract extensions are meaningless when a guy can get fired at any time. Its all a facade.
But you said Ross was sending a messing. IF you are "sending a message" as you said of "improve or you're out", it makes zero sense about the extension. That's just not reality.
Bottom line, Ross F'd up with the Harbaugh thing. Got heat from everyone in the NFL and the media and fans. So to make nice he gave Tony a big extension. No message was being sent, just that Ross was trying to buy his way out of bad PR. Nothing more, nothing less.