一个帖子的主题可以归入两个类别吗？

[sam (Sam Saffron)]

@ChristopherMcEwan

but my question relates to allowing a topic to not be restricted to a single category for situations where, as in the example, the topic could logically reside in more than one category

This is a completely impractical change that would cut deep into the internal structures in Discourse. The entire code base is designed around the concept that a topic has at most one category, changing this premise is very very unlikely to happen.