Myself, I’m not really moved by the claim that publishing standards were so different 6 years ago that Elsevier has clean hands here. It’s pretty obvious from this response that Elsevier was happy to take money from Merck to make something journal-like, trading on Elsevier’s reputation as a publisher of proper journals. And the “no plans to look further into the matter” comment does not really speak to an awareness by Elsevier that its reputation as a publisher of proper journals is damaged by shenanigans like this.
This is the kind of thing that makes you wonder if the model of journal publishing for profit ought to have a future, at least where scientific and medical journals are concerned.
I think the only recourse here is actually to shun publication in journals owned by Elsevier. Certainly, that’s what I will be doing (noting that the big journal in my field – Journal of the History of Biology – is published by them and that I have been working on a manuscript that I intended sending there).