So, if the extractor strikes the firing pin - what does it matter if you attempt to catch it in the air or let it fall to the ground? If it's gonna go, it's gonna go - and you'll probably get hurt. This thread's the only place I've ever heard of any such (rumor of) occurrence.
Sorry, not a rumor - it's quite common. And the problem is your hand causing the round to bounce around in the ejection prot. Jerking the slide and ejecting the round out with force is not the same thing as holding it in to the side of th port - it's not "gonna go" either way. And getting hurt may not concern you, but how about touching off a firecraker at 10pm in a hotel room? The manager and the local PD night shift might just find that of concern.
Covering the ejection port will become your habit if that's what you do. It will find is way into your tap/rack if you unload your gun more than you practice that. Covering the ejection port causes malfunctions! Moving the slide backwards slowly causes malfunctions!
Trying to catch a round may work 99 out of 100 times, it's that last one where a person tries to juggle a round in the air that problems will occur. I've seen it too may times to advise anything other than DON'T DO THAT. The operators focus becomes catching the round rather than muzzle control and where their trigger finger is. And the worst is when someone fumbles and ends up dropping the round - they bend right over without concern for anything other than picking up that "precious" round that fell through their hands.
I'm not going to argue about it here any more, but I will state my opinion a bit more sternly before I take my leave:
Catching the round while unloading a pistol is amateur hour. It's not in any way a "safe" practice, nor is it in any way worth the risk. Jerk the slide and let it fly, once you've delt with the pistol and secured it, you can concern yourself with picking up your formerly chambered round.