When would you resort to using 'his comment' and when would your resort to using "his comments" in a sentential situation similar to this:

His comment or comments on that issue has been baffling.

Thank you.
If he only made one comment, then you would say "His comment on that issue is/was baffling"

If he made several comments, then you say "His comments on that issue are/were baffling".

Also, I can't really think of a situation where I would say "has been baffling". It would be more along the lines of "I am/have been baffled by his comment/comments on that issue."
Opinion and comment(s) are not quite synonymous in this context.

For example, if someone said she hated lasagne because it tasted of car tyres, smelled like baby sick, had way too much saturated fat, and tended to drip down her shirt when she ate it - that would be one opinion, but 4 different comments about lasagne.
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Thank you, Tidus.

How can you tell if a person has made a comment or several comments when the definition might go "When you make a comment, you are expressing your opinion on it." To me, expressing your opinion one time may take a sentence or many paragraphs.
 Lil' Ruby Rose's reply was promoted to an answer.
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Thank you for offering an opinion full of comments.