This gemara flies in the face not only of the vital concept of free choice, but also of verses in the Torah itself which indicate that Bnei Yisrael accepted the Torah on their own volition. The appropriate analogy is a drowning man to whom a lifesaver is thrown. He still has the choice not to accept the tube, but no sane person would do so. In many ways, the month of Tishrei is comparable to that Sinai experience. Apparently, after that intense feeling of closeness fades, so does religious commitment.
Every moment has the potential for sanctification.
Every moment can become Tishrei. The very idea of times where Hashem is more present than others must be reexamined. From His perspective, He pervades all of time and space. If one looks closely one can see that Rashi is using the mashal to describe the relationship between Hashem and Bnei Yisrael. In order to understand the nature of this relationship we must explain the idea behind the entire holiday of Sukkot.