Well even though functional programmers realized the connection to functional operators when they first saw the LINQ syntax (at least select is map and where is filter) the adapted naming could have helped popularize LINQ because it then looks more than SQL. I don't know if that's true but some irony it would be if that now makes it stand out as different among a family of "LINQ-like" implementations. These are just names though.
Also, does SQL have to be based on sets to be sound? (Order Theory?)