Alameda is not a suburb of SF. Stupid writer obviously doesn’t know the Bay Area
They’re using the “commuting distance” redefinition of the term, most likely.
A suburb isn’t “associated” with the urban area in its proximity.
Here’s the Merriam-Webster definition for you:
“an outlying part of a city or town; a smaller community adjacent to or within commuting distance of a city”
Alameda is indeed a suburb of SF.