Towards the end of the article, he was advocating why heter mechira was preferable over other options. IIRC, the reason to prefer heter mechira over importing from outside of Israel was because it's a mitzvah to eat the holy shmita produce (according to Ramban, hasagos al sefer hamitzvos, third mitzvas aseh).
I remember being puzzled by this at the time. One basic premise of the heter mechira is that land owned by non-Jews in Israel lacks (full) kedusha and therefore there is no prohibition of shmita (like Rav Yosef Karo's opinion, which is followed by "minhag yerushalayim.") That's why selling to a non-Jew would help at all. So to the extent that the produce has no shmita sanctity, how can there be a mitzvah to eat it?
Therefore I would like to clarify:
- Did Rabbi Aviner actually make this claim? Is there a copy of his drasha available including this specific claim?
- Are there legitimate halachic opinions which say that the mitzvah of eating shmita produce (according to the Ramban) applies even to produce from non-jews, ven according to the Rav Yosef Karo's position in which are treated as if they lack sanctity? (Of course, according to Mabit that non-jewish produce is still kadosh, the mitzvah would apply. I'm asking specifically according to the Beis Yosef.)
(Another possibility- perhaps Rabbi Aviner is assuming that the sale doesn't really work to actually make it owned by non-jews, and thus it still remains with the original kedusha; and yet the heter mechira would still be valid as a rabbinic "fake sale" or ha'arama)?
Update: This is the article that I remembered seeing. In it he is clearly advocating relying on heter mechira as the proper course and obligatory, not just as a leniency.
At the end when discussing not buying from outside of Israel, he finishes off by saying:
I also learned that there is holiness in the fruit of the Land of Israel (Bach Orach Chaim 208) and even more so in the fruit of the seventh year according to the Ramban. Notice I did not say that I am holy. I am a regular Jew, but if The Holy One, Blessed be He, decreed that when I act like a regular Jew and when I eat fruit of our Holy Land, I absorb holiness within me – this is His will and I am happy to perform His will.
It is true that he is not addressing the "mitzvah" of eating fruit, but rather that there is holiness in the fruit. The Ramban says that the mitzvah is to eat the holy fruit. However, The question still remains- what is the source to say that the fruit which grew in a non-jewish field still (according to Rav Yosef Karo) has the kedushas shviis?