It also depends on the situation. He's said that he's looking for several small sites to provide extra income meaning that he's looking at it from a cash-flow perspective. From a cash flow perspective, hosting cost definitely is a factor.
This is the specific type of situation that PHP is almost ideal for because it scales down better than most other languages since everything is loaded and processed on-request instead of booting up to preload. You can host 1,000 PHP sites on a single small server as long as the concurrent traffic doesn't outstrip the specs. With most other languages that have to boot and preload, you're restricted before traffic becomes a consideration.
PHP's not the right choice for every situation but for his use case it's pretty solid.