From what I've been browsing thru on other forums, USCIS has elevated scrutiny of EOS\COS applications. OP had stated in another forum that they used 'travel and tourism plans' as a reason for the extension request. Such thinly-veiled frivolous requests generally earn a denial; extensions are primarily intended for medical/life-death issues, not more travel and tourism. With i539 adjudications taking several months, overstaying past the i94 date is irresponsible. A denial here would risk their visa.