First, it's Irvine who says "silos," not the submariner. Second, a web search quickly found that there are silos on subs.
"The submarine has a double-hulled configuration with missile silos housed in the inner hull."
The quote in the article is an indirect quote of the "retired petty officer" who if familiar with VLS, would call the tubes launch tubes, launchers or VLS system, unless he wasn't in the US Navy.
It is a hole in the story I can't accept.