I thought that perhpas the use of the gerund, "limiting", makes more sense in the context of the sentence. Use of "and limits" would be correct if the sentence meant that there are 2 reasons the skeptic uses "to be" as he does, and those reasons were that he suspends judgment on the existence of good, bad, etc, and the other is that he limits himself to basing his value judgments on the ways things appear. If that were the sense of the sentence, grammatically parallel construction dictates that "suspends" and "limits" both be used in the present tense. However, this sentence means that the skeptic uses "to be" as he does because he suspends judgment on the existence of good, bad, etc, and that, consistent with that, or as a consequence of that, his value judgments are based on the way things appear to him. I thought this meaning more plausible because the suspension of judgment and the limitation of value judgments are so close as to be duplicative if stated as different reasons for the Skeptic's use of "to be" in the sense of "to appear". Hence, perhaps the subordinate clause beginning with the gerund could show that what follows in the sentence is in accordance with what's been said in the main clause.
Sextus