H alpha,
You're right that the single-epoch released image just looks like a wave. The Australian government person interviewed said that the two objects appeared to be "awash", which implies multiple views to see this happening. Then again, a stack of containers, or an upturned yacht would be "awash" too.
I think it's reasonable to assume that there is much more imaging available; however, the resolution of the images released is of order of a meter, at least for sunlight reflecting off the surface, so it's probably adequate for the purpose. The tone of the Australians today has certainly been very positive. It seems hard to imagine they'd have made a statement/released the four-day-old image if they weren't quietly confident of finding wreckage.