Does beer expiration change based on yeasts? Part of my job involves selling beer. I was told by a coworker that visible yeast particulates at the top of a beer bottle indicate that it's not fit for consumption, whereas yeast at the bottom is fine. 

Is this true? And if so, does it change depending on whether it's a top-fermenting or bottom-fermenting beer? Does this affect meads and ciders as well?
Quick answer no. The yeast used should have very little effect on on the expiry date. Things that will affect this more are:


Temperature of fermentation
Hot side aeration
Cold side aeration
Pasteurization
Filtration
Colour of bottle the beer is stored in
Type of beer ie % dark malts
Live product vs sterile filtered


This list is incomplete. This is an incredibly complex subject, there are PhDs in Brewing/Chemistry handed out for small aspects of each of these topics.

Here is a quick overview presentation of the technical aspects surrounding beer stability and stabilisation. 

https://www.craftbrewersconference.com/wp-content/uploads/2015_presentations/F1420_Deniz_Bilge.pdf