Only a good idea if they immediately convert to fiat, at which point they'll lose out on advantages of a price rise. However, the alternative is worse, as it's pretty easy to lose percentage points in value on any given day. I'd hate to be the guy who had to explain why yesterday's $1.00 payment was now worth $0.97. Perhaps a hedge would be to tie your paycheck to Bitcoin's value at the beginning of the pay period.