Rule learning approaches for knowledge graph completion are efficient, interpretable and competitive to purely neural models. The rule confidence aggregation problem aims to find a single plausibility score for a candidate fact predicted by multiple rules. Despite its ubiquity due to noisy and large rule sets from data-driven learning, the problem is underrepresented in the literature and lacks a theoretical foundation. In this work, we demonstrate that existing aggregation approaches can be expressed as marginal inference operations over the predicting rules. In particular, we show that the common Max-aggregation strategy, which scores candidates based on the rule with the highest confidence, has a probabilistic interpretation. Finally, we propose an efficient and overlooked baseline that is slightly superior over the simple strategies.