I did RTFA, did you?
Their reply, "We only accept Apps which uses our API. A workaround like this is considered a hack. Please have a read of the Panasonic VIERA CONNECT License Agreement, Section 2.4." From their T&Cs Section 2.4, "(iv) Licensee Application may only use Panasonic APIs for the sole purpose of developing one or more Licensee Application to be made available on VIERA Connect Platform (for the avoidance of doubt, Licensee may not use Panasonic APIs for any other purpose other than developing Licensee Application)" Also from the FA, "Their 'API' is just HTML, CSS, and Javascript." The OP relates that they claim jQuery was "not standard Javascript." confirming that 'standard' Javascript, and not use some independent Panasonic API, is their expectation. Their reply does not mention using XMLHttpRequest as being a violation.
jQuery is just a bunch-o-Javascript, uses only Javascript features, and does not seek to 'workaround' anything, and therefore only uses their 'API'. If using jQuery is a hack then, by their own definition their web site is a hack.
I think their real problem is that the half-arsed automated scripts they use to scan for obvious malfeasance are too broken to actual parse jQuery shorthand, that the reviewer is a muppet, or that there are numerous unwritten rules governing their 'API'.