And what makes you think that?
Look at the engine exhaust. It’s positioned over the wing, may hide the IR signature. Also some diffuser device that redirects the exhaust gasses, reducing the IR signature.
Two things, the SA-7 is only good for a target that either doesn’t have counter-measures, or doesn’t use them. This helo has them and the deployment is likely automatic. Also it spends its time low level. SA-7 is super elevated before launch, its seeker sucks and unlikely to pick the helo out amongst the low level IR sources. The SA-7 like most manpads has a significant signature when fired and this has enough ordnance to make the launch the last one for the launchee.