I'm sorry that you felt the need to ask. The comment didn't add anything to the discussion. Had the profanity been replaced with more tactful language, it was still a candidate for removal. I would have deleted it without a second thought.
To address your question, the fact that the comment contained profanity was not in itself reason to flag it. If the comment were contextually appropriate, the existence of the word fuck would not necessarily qualify it for flagging. The commenter's word choice was intended to provoke a particular, graphic reaction to demonstrate the crudeness of the innuendo. Because the commenter was explaining what the sexual innuendo was in an illustrative way, it is in the decidedly grey area of use-mention.
In this case, I would recommend that if it bothers you, flag it with the 'other' flag and ask a mod to review the wording to determine if it can be amended in such a way as to preserve the original information without using crass or vulgar language.
In response to some of the extended commentary here, I want to put to rest the notion that you should even care about how much work this creates for the moderation team. For one thing, if enough of the community agrees with you that something is offensive, the comment will be automatically deleted and we won't even see the flag. For the other thing, it is one of our responsibilities to handle flags. That's part of what we do, and that's why we just had an election to bring on more mods.
We won't know what the community finds offensive unless you flag it for us. If there is a lot of offensive content, we need to know about it, regardless of the amount of work it creates for us. That said, tread lightly with the offensive flag. Use-mention can be a sticky wicket. If you aren't sure, you can use the 'other' flag to write us a note.