Using Bitcoin to pay employees' salaries shows the government's recognition of Bitcoin, which has a positive impact on the development of Bitcoin.
When employees obtain Bitcoin, they will trade in their daily lives, increase the circulation of Bitcoin in the market, and make more and more people aware of Bitcoin, which is conducive to the future development of Bitcoin.
They also have the choice not to trade those salaries that they receive. I've read some interviews that the guy was being paid with bitcoin and he doesn't want to spend it.
But as much as he can, he's saving bitcoin because he knows the true potential of it. He's just a common guy but still aware of the risk and the volatility of bitcoin has.
If he have that knowledge and enough trust with what this crypto currency may bring him, keeping all or big portions of his payment might bring him the retirement money that he's desiring.
We can say that those who have that idea about this industry, they'll be thankful as the mayor gives them the opportunities to hold good amount of assets that potentially will grow after some time.
Good move if looking in the positive side, this kind of gesture brings more attention to other people who don't have any idea about this market.