Well, yes and maybe no.
Since they all seemed to stop working some time last week, I suspect it was an update by WU that broke them (or stopped accepting whatever they were sending). Yes, Acurite will have to comply with whatever change WU made (e.g. with a firmware update). If this is what happened, it is IMO bad s/w development practice for WU to just update w/o testing and/or notification to users and mfg. knowing it would break some stations that were working.
If Acurite has the ability to update firmware w/o user consent (and did that w/o notification to users which broke the WU updates), that would be bad device management practice on multiple counts.
There is more to this story, but I doubt we will ever know what it is (unless someone from Acurite or WU reads this and cares to discuss.