[Pontiac]

They may be thinking of observers in this neighborhood

In order to read the message the reader would have to be close in time and space (Cosmically speaking).

The writer would have to have a relatively specific time and place in mind for their intended reader to appear for this theory to work.

If these scientist are not talking about God/Creator who are they talking about?

[RightWhale]

"Our work does not support

I suspect they have done no work at all. If they had found a message they would say so, otherwise they are speculating or seeking grant money.

[planetesimal]

It's not your common or garden nebula, it's the universe. I don't think line of sight and distance matter one whit.