I'll answer you seriously.... for years I thought it was until I read that the song was rewritten and only the chorus was kept & a few verses.

I clearly hear Jon in the Chorus. If the verses were rewritten, why would Jon sing on them unless he sang on demo or completed a version? It might not be Jon but the singer trying to sound like Jon. Listen closer. I need to be certain.

Edit - Here is the story behind it:
“There’s five writers credited on that song. There were only three in the room, me, Paul and Richie,” Jon recalls of the original writing session that produced “Notorius.” “It was a rock song when it left my house. It turned into I don’t know what when it got to Canada. They rewrote it lyrically. The only thing they kept was the chorus and a couple of the key lines in the lyric…The song changed from an AC/DC free vibe to Loverboy which was different. We were disappointed because the song reached the top 40 but not much higher. It was a much better song we felt when it left us.”