I just realized I mischaracterized how constrained is implemented in Asciidoctor. Here's the regular _expression_ it currently uses for strong:
Thus, in fact, it does work the way I was implying it should. The formatting pair must be bounded by non-word characters and there cannot be a space directly inside the formatting pair (which is even broader than looking for word characters as I stated). It doesn't consider what punctuation might be there at all (unless that punctuation is defined as a word character, which is another matter).
So the following example works today:
But the current definition is quite clearly too difficult and nuanced (even for me to remember off the top of my head) and it certainly demands clarification.
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