I think Dick Rose correctly pointed out that Rob has swapped B and Y in part of his analysis.  Clearly Rob is describing Y when indicating she turned downwind, such that I certainly understand what he means and didn't even notice it the first time I read it.  Rob assures me he will review his post and correct the mistake.

Actually, it was worse than that.  I also misquoted rule 18.2(d), later in the article.  I've fixed both these problems, and hopefully my analysis is now free of typos.

I think there (in the sixth paragraph) is another typo - the word "course" instead of "mark".

The question remains whether the same ruling would apply if B had attempted to keep clear, rather than holding her course.
When Y regains mark room does she need to give B room and opportunity to keep clear?

In the given instance Y was briefly on starboard gybe and thus, in the interim, had ROW, so the question is muddled.
(The same result may have come for a different reason.)
But take the opposite approach, pictured here.

Y instead is briefly on port gybe without ROW and mark room is suspended.
Y then gybes back to starboard, still without ROW.
Y here resumes mark room, rather than acquiring it.
Does Y have a new maneuvering obligation to B?

Boris, thank you for finding that error; I've now fixed it in my post.  I swear, I read and proofed that post numerous times over 3 days, before I put it up on the blog.  I guess I should have proofed it at least one more time!

Phillip asks whether, in his new scenario, there's any requirement for Y to give B time to react to Y's newly-obtained mark-room at position 3.  I think the answer is "no".  While rule 15 requires a boat that acquires right of way to initially give the other boat room to keep clear unless she acquires right of way because of the other boat's actions, there is no similar broad restriction on a boat acquiring room.  There is a strangely specific rule, 18.2(f), which says "if a boat obtained an inside overlap from clear astern or by tacking to windward of the other boat and, from the time the overlap began, the outside boat has been unable to give mark-room, she is not required to give it."  In Phillip's scenario, Y does not obtain her overlap from clear astern nor does she tack, so that rule does not apply.  

I don't buy Phillip's argument that Y "regains" mark-room rather than acquiring it.  We use the expression "acquire" in many situations where a boat loses right of way and then gets it back again, as for example when two boats are running downwind in big waves and one of them repeatedly establishes and then loses a leeward overlap on the other boat, from clear astern.  Although she is clearly regaining right of way, we still apply rule 15, which uses the term "acquire".  

In Phillip's scenario, though, I'm not sure that Y doesn't break rule 10 (Port/Starboard) at position 2 -- it certainly looks as if B takes avoiding action at position 2 because she has to do so. If Y does break rule 10, she is not exonerated because she is not sailing within room or mark-room to which she is entitled.