True enough, nevertheless the targets did deploy a rather massive quantity of flares, which is consistent with a very high level of IRCCM from the missile. This is also echoed in all of the literature I have read on the subject (eg. the source I attached to that same post) indicating that imaging infra-red (IIR) seekers like the one on the AIM9X represent a generational step above those you might be used to on missiles like the AIM9M, R73 or Magic II, with a corresponding jump in IRCCM capability. This is also reflected in the trend toward IIR guidance found in numerous current and emerging SRAAMs ranging from the AIM9X to Python 5, ASRAAM, PL-10, MICA-IR and possibly K74M2.
I am not aware of any data indicating that pre-emptive or reactive use of DCS-style pyrotechnic flares (as a missile seduction measure) should provide an effective method of defeating such missiles, even in scenarios like the one you have shown above. The closest thing I have seen proposes that the use of a distributed flare (ie. not the type depicted in DCS) may provide the target with a fleeting opportunity to break the missile's lock (at ~600m or less from impact) by momentarily bleaching out the seeker of an IIR missile approaching from the rear, giving the aircraft a last ditch chance to break away from the missile FOV. This is not what you have depicted above though.
The take-away message (p7) seems to be that DIRCM systems like the one on the Su-57 will be needed to provide an adequate level of protection against IIR seekers going forward (and even that might not be enough). To quote the source I just described:
Nevertheless, if you know of any high quality sources/data supporting your position by all means present them. In the absence of this all you are doing is arguing from incredulity, which probably won't lead to any significant changes being made in DCS.