If he was talking about compact cameras then I'd agree with him. The manufacturers stuff in extra pixels will seemingly little* regard for increased noise. They want to have a bigger megapixel number.

With DSLRs it is different though. The manufacturers tend to add extra pixels, while at the same time improving other parts of the sensor/processing to compensate for the smaller size sensors. So each step increase in pixel density typically comes with the same** or lower noise that the predecessor.

The sensors in today's 18 megapixel APS-C DSLRs have less noise at 800 ISO than my 9 year old 6 megapixel APS-C DSLR has at 200 ISO.

* that isn't to say that they aren't also making improvements in noise along the way though, the small sensors have over time got less noisy generally as well

** though even with DSLRs there is the occasional exception of sensors in a range getting noiser, but that isn't typical