In a typical downwind finish with rule 18.2(a), since an overlap existed at the zone, orange is entitled to mark-room since she is the inside overlapped boat. However, in this case you have to get into definitions. The definition of mark-room is the room required to sail to the correct side of the mark on a proper course. The definition of proper course is the course a boat would sail to finish as soon as possible in the absence of other boats. So, would it have been faster to soak or to continue and gybe? Not knowing what kind of cats these were, my guess would be soaking would've been slower. This is not about what orange "wanted" to do, its about what she should've done in the absence of other boats. Now, if blue sailed in a way that kept orange from gybing when she should've to be on her proper course, then Blue fouled. I wasn't at this situation, but I've seen the same thing 100 times. The onus is essentially on Blue to prove that she didn't foul Orange. You can bet that Blue would get chunked in a protest room.