This was taken from a non-Catholic commentary (Pulpit Commentary), the thoughts seem to be consistent in many commentaries, Catholic or not - what your friends suggest is a misinterpretation:**
Not to think of men above that which is written**. The true reading is merely, not above the things which have been written,as though the words were a sort of proverb, like Ne quid nimis or Milton’s “The rule of not too much” (μσηδὲν ἄγαν). The word “to think” is omitted in the best manuscripts. The phrase, “which have been written,” is of very uncertain meaning. It may refer generally to “the scriptural rule” that all boasting is wrong (Jer. 9:23), or to the humble estimate of teachers which he has just been writing down for them. All his Old Testament quotations so far (ch. 1:19, 31; 3:19) have referred to humility. The text, like so many others, has only a very remote connection with the sense in which it is usually quoted
