Lube isn't going to help if it's floppy. I thought everyone knew that?
The article says about an eject button, these only came on the 3.5 drives, hence the disk was a stiffie.
In this case, clearly the user was inexperienced and didn't know the required amount of force or technique to get it in and out of the slot properly.
The 5.25 drives had flaps covering the slot but later ones used knobs to lock the slot closed. Luckily neither suffered with the head-slap problem that was common on their former 8 inch counterparts. This fact alone made it difficult to use them in quiet office environments.