Thanks for the investigation! Yes, that would be the way to disable transforms inside a quoted s-expr.
But I think that still would leave issues. For one, it is approximately as likely that a list innocuously contains a literal '+ as that we're constructing a fragment of code that is eventually intended to be eval'd. We need a way to say, "this is code" or "this is never going to be eval'd." A second issue is that quoting isn't the only way to read data. Imagine using read to read a list from a file. How would we suppress infix there?
I actually think reading data from a file is the bigger issue. Small quoted lists in code will be noticed, and can be replaced with some (klunky) combination of list and cons. It's far worse if you have a multi-megabyte file that silently gets corrupted because of one character.
