[SAJ]

On the same premise, it would be quite proper to fire someone who dyed their hair, wore an unattractive perfume, participated in drag racing in their off time, thousands of things.

ANY voluntary behaviour could (and would, ultimately) become grounds for dismissal if this lot go on unchecked.

[Arkinsaw]

ANY voluntary behaviour could (and would, ultimately) become grounds for dismissal if this lot go on unchecked.

Anything they deem might someday affect your insurance payout would be fair game to prohibit in off hours. In fact, sitting around in a chair typing in a web forum in your private time and not exercising instead would be one. I suppose you will need to install a monitor on your CPU or your chair or body to see how long you spend sedentary during your off hours.

It is a short step from prohibiting behavior on the basis of healthcare costs...to requiring behavior on the basis of healthcare costs.

[Young Scholar]

On the same premise, it would be quite proper to fire someone who dyed their hair, wore an unattractive perfume, participated in drag racing in their off time, thousands of things.

You don't think they should be allowed to fire people for those first two? Those aren't even off-time activities, they are things that directly affect the work environment and the atmosphere/image of the company.