Chlamydia come in sexually-transmitted and non-sexually transmitted types. The most prevalent non sexually transmitted species is Chlamydia pneumoniae which, as you might imagine, causes pneumonia.
Since the "case definition" of SARS will capture large numbers of pneumonia cases who don't really have SARS, it's not surprising that some cases of pneumonia caused by Chlamydia pneumoniae are showing up.
What this has to do with STDs is-nothing.
The evidence that a novel virus, probably a coronavirus, is the singular cause of SARS is quite strong.