I think she meant the conditional phrase "if you love the English language as I do" to be taken as a whole, in which case the phrase "as I do" within it is a restrictive, nonparenthetic phrase. Of course, if she intended "as I do" to be nonrestrictive, it should have commas fore and aft as you suggest, but the meaning would be different. The comparative aspect would disappear from the phrase and it would sound as if Julia was saying that if you love the English language, you'd love having at hand the type of book that Carillo has written. It's clear, though, that she thinks it's enough for people to just love English to the degree that she does to appreciate Carillo's book. And I must admit that I'm rather comfortable with that idea as it is.