The Gemara initially thought that R. Yanai permitted killing snakes and the like outright, in which case Rebbi's statement must have been in the form of a praise. But it concludes that he may well have permitted killing them only by treading on them whilst walking (which the Nebate'an did not do), in which case, he meant to degrade him. This leaves Rebbi's statement ambiguous, implying that we really don't know which of the two he had in mind.

On the other hand it is possible that based on the continuation of the Sugya, which seems to conclude like the second interpretation, Rebbi's statement was meant derogatively.

Most likely, that is the final outcome of the Sugya.

May you and yours be inscribed in the book of good life.

Kol Tuv

Eliezer Chrysler.