From what little I could get from the abstract of the Science paper, this paper shows that in this case, you can’t go back to the earlier form by just making a single mutation. Nothing having to do with what you put in the false title.
Why don’t these rags spend the $ for a journal subscription and set it up so you can view the source material for free?
Why they don’t- because then people would read the paper and see that these creationist fishwraps are what they are, the equivalent of the Weekly world News.
No, I think that the letter states that unless the 5 specific restrictive mutations are reversed a non-functional protein is produced when other "key function switching" mutations are reversed. IOW there is a definite order of mutations. Thus even with selection for the old function the protein will not evolve the old function, "You can't get there from here."
A ---> B is allowed.
B ---> A is not allowed.