Ecm against missiles' seeker doesn't make sense to me, considering the size of the arrays and likely wavelengths involved.
However, stand off ecm platform that is geared against larger aerial radars, possibly up to UHF, as used by the E2, meant to temporsrily blind the tracking abilities of the enemy, does sound plausible, if not likely.
So part of the fleet would stay mostly static, in the background and keep the arrays of one 055 turned to the enemy. During that time, other part of the fleet may try to come closer to the end enemy, hoping it is somewhat protected by the powerful stand off jamming.
Certainly no plane could hope to create enough power to jam in similar fashion, nor stay present long enough.
One of many Questions to that idea would be: why can't the radar arrays be used for jamming as well? Could such separate arrays be justified just for that part of the spectrum up to UHF?
Though, if anyone would be prepared to use 055 as stand off jammer, then perhaps even a radar role isn't out of the question. Used defensively, near Chinese coast, espcially if part of more numerous force, such 055 could very well afford not to turn around to scan but mostly just sail up and down the coast, 100 or 200 km away from coast, looking for stealthy targets and giving the coastline another buffer of protection or extra warning time...
Ultimately, all these are just fan theories that may well be pure fiction. I fear it may be years before we learn of real purpose of those panels ...