I'm not Nancy Salomon (obviously
), but I think I can explain this by giving an example out of Stan Newman's book Cruciverbalism
. Merl Reagle recalled using EYELOVEU as an entry clued as "Optometrist's cherished alma mater." This is a pun entry, punning off the well known phrase "I love you."
If this were a thematic entry (not sure what else you could use here, maybe EARSTOU?), Nancy is saying it would be fine (at least if the puzzle theme is based on puns, like Merl's NYT puzzle for The Simpsons
). But since it's not a theme entry, and "eye love u" isn't a real phrase, it isn't a "straight" fill entry, and therefore verboten...
...except that Will Weng apparently allowed it. Well, she did
say she deferred to Merl as the expert on puns.
Does that help?