The club's record goalscorer admits Monday's announcement of Kinnear's resignation was unsurprising news, but was shocked that Kinnear was appointed in the first place.
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"That's life at Newcastle United," Shearer told BBC Radio 5 Live.
"I shouldn't say I'm surprised but I was surprised in the first place when he was announced director, particularly the way the news was broken when Joe himself announced it on the radio when he got some of the players' names wrong.
"What has he been there now, about seven months? And two players have come in, albeit both players on loan.
"Maybe it's Newcastle's way of trying to say that the performance on Saturday wasn't good enough and why they didn't get any new players in, maybe that's one of the reasons.
"But they can only get players in if there's one man prepared to sign a chequebook."
With Newcastle still licking their wounds following the 3-0 derby defeat to Sunderland, Shearer concedes that uncertainty continues to plague the Premier League club.
"You just never know what goes on at Newcastle behind closed doors," he said.
"I think we were all surprised because Joe had been out of football for so long. Let's say that we hope he's okay and it's nothing to do with ill-health but it's just bizarre sometimes at Newcastle.
"Four, five weeks ago Newcastle were going so well, still in the FA Cup, Alan Pardew was getting manager of the month awards [and] they were looking up the league rather than finishing in mid-table.
"It's amazing what happens in three or four weeks in football. The 3-0 on Saturday hurt everyone and they were second best all over the park with a lack of fight and a lack of desire from the players and now it's come to this."