Has there been any confirmation that these "zombies" even will be hostile towards the player? They might look like they just want to eat your brains, but there is a chance they actually are intelligent and have just been discarded into the mines(?) as failed experiments.
If this was the case, it would be pretty normal that someone who had been living in a damp dark place for years or even decades, was scared by seeing another human being.
And i noticed something on the video aswell.
Doesn't that look a bit... twisted to be a normal potted plant?