"They said the action itself is illegal and they're beginning their enforcement actions at Coinbase" - they said no such thing, stop guessing out of your backside to try to strengthen phantom arguments.
Suing Coinbase first -> "beginning their enforcement actions at Coinbase"
Which exactly fantom argument is 'the first page of the Securities Act of 1933'?
Do I know for a fact they're going to go after everyone else? No, I don't work there, time will tell.