If the current owner was actually using the name for his business, I'd agree with the majority of commenters in this thread. Say he had a consulting firm named "WorkBetter, Inc." and had been using it for years with business cards, receipts, and tax records to show for it. That does not appear to be the case here, as he has
a list of domains that he's trying to sell. 117 of them by my count, including several with active trademarks and a few
Daft Punk-ish variants of work-something.
This is textbook cybersquatting. He bought a whole bunch on speculation hoping to get rich quick, and now wants to cash in his lottery ticket. It's a little too late for him to claim he has a legitimate business use for it.
I know that's not the prevailing opinion here, but he's been squatting on the domain for years without using it. I think the company suing him has a legitimate case. It doesn't and shouldn't matter that he held the domain before the plaintiff registered their trademark; his continued holding of it is squatting.