the meaning of "naval"

The meforshim struggle to make sense of the expression "Vayinabel tzur yeshua'so." (32:15)  The word "neveilah" is something you would normally associate with a physical thing.  Here, the pasuk is referring to disrespecting G-d, so it has to be taken less literally, which is how Rashi and Seforno interpret it.  Ibn Ezra sees a connotation of chilul Hashem.  The Meshech Chochma writes that the pasuk is referring to scoffers who go around attributing ridiculous meanings and interpretations to Torah so that it becomes an object of ridicule in people's eyes -- they make G-d repulsive to others.  What caught my eye is the Ramban, who reminds us that earlier in the perek (32:6)  Bnei Yisrael themselves are referred to as an "am naval v'lo chacham."  Ramban there writes that the term "naval" is the opposite of "nediv."  A naval is someone who has received gifts or consideration, but repays it with animosity and disdain rather than a thank-you.  A naval never shows appreciation.  Our pasuk is stressing that G-d acted as "tzur yeshu'aso," your redeemer, and yet, "vayinabel," rather than give thanks, we turned our back on him.

I want to suggest another possible interpretation to this ambiguous phrase also based on the earlier pasuk.  The Targum Onkelus explains the phrase "am naval" as "the nation who accepted the Torah."  How do you get that from the word "naval?"  The Peirush Yonasan on the T. Yonasan writes that the idea is that despite our receiving the Torah, we remained devoid of wisdom.  If so, ikkar chaseir min haseifer, because the translation of "naval" is missing.  The GR"A brilliantly  connects the Targum to a Midrash (in B.R. 17) that refers to there being three "novlos": 1) sleep is the noveles of death; 2) a dream is noveles of prophecy; 3) Torah is noveles of Heavnely chochmah.  The word "noveles" means an unripe date that falls off too early -- it's a taste of the real thing, but has not yet blossomed to fruition.  "Am naval" means we are the nation that got that noveles, i.e. the Torah, which is the noveles of the ultimate chochmah, but then we did not take advantage of that wisdom.  Turning to the our pasuk, although the Targum does not say it here, perhaps we could explains "vayinabel" to mean that we turned G-d's greatness into something unripe, something less than ideal, i.e. we minimized it's significance.