better to face off against a baal bechira than a wild animal?

We've discussed many times before (e.g. see here, here, here, and here) the following famous Ohr haChaim, based on Zohar: Chazal tell us that the pit that Yosef was thrown into was filled with snakes and scorpions.  Why then does the Torah credit Reuvain for saving Yosef?  All he did was take him out of the frypan, out of the brothers’ hands, and toss him into the fire, into the scorpion pit?  O.C. answers that Hashem has complete control over animals and everything else in the natural world, and therefore if Yosef didn’t deserve to die, the snakes and scorpions would not be able to harm him.  However, a human being is different because he/she is a “ba’al bechira,” and Hashem does not interfere with free choice.  Had Yosef been turned over to the brothers or other people, even if he didn’t deserve to die, they would still have been able to harm him had they chosen to do so. 

If the O.C. is correct, what's pshat in 7:22 that Hashem will not allow us to conquer the goyim in Eretz Yisrael too quickly  לֹ֤א תוּכַל֙ כַּלֹּתָ֣ם מַהֵ֔ר פֶּן־תִּרְבֶּ֥ה עָלֶ֖יךָ חַיַּ֥ת הַשָּׂדֶֽה׃ , lest the empty land be overrun with wild animals?  Sounds like it is better to have to deal with the goyim who are baalei bechira, than with the wild animals, who are not, exactly the opposite of the O.C.!?  (See Taz in Divrei David, Targum Yonasan)