Engine stall and bad starter combined?

I understand these motors have a tendency to seize or break a rod and blow a hole in the block. This one hasn't done that. The car showed zero issues prior to failing. It had its routine oil change, drove 40 miles home, went to leave again and it shut off in the driveway and wouldn't restart, no crank either, not even a click. We first determined the starter was bad. Checked to ensure the motor would rotate manually first then replaced the starter but didn't fully reassemble everything like the skid plate and what we thought was a o2 sensor that attached to a bolt in the starters heat shield. When we attempted to restart, cranking sounded off, then after several tries, we got it to start but it was missing extremely horribly, ran rough for a couple seconds and shut off hard. My husband thought it had seized then, but a few minutes later I was able to crank the motor again but didn't attempt to fully start. Now he thinks the motor is 'blown' and so did a small-town mechanic. My question is would a bad (or disconnected) camshaft sensor or crankshaft sensor mimic a motor with horrible timing that some may assume was a 'blown' motor on just a glance or 2 seconds of very rough running? Thanks