Not really, they're still proportional to the average wave height. So while you could always be at risk for rogue waves, the sea has to be quite rough before a large vessel need be worried about them.
Do you have a citation for that? The definition of a rogue wave is a function of existing conditions, but that doesn't exclude a rogue wave in calm conditions; it just requires a greater height in rougher seas.
Intuitively I would expect rogue waves to be more likely in rougher seas, but it's another thing entirely if the physics of rogue waves requires rough seas locally. I don't disbelieve you, but an explanation of that claim would answer a ton of questions about how rogue waves form (answers missing from the Wikipedia page, which seems more inconclusive) and a page worthy of bookmarking.
EDIT: Your claim seems consonant with the "linear" theory of rogue waves, but as the Quanta article explains that theory is contested by proponents of the "non-linear" theory.
I think I see the confusion, rogue waves, by definition, are just waves much larger (twice as large, again from the definition) than the surrounding ones, sufficiently so that they're impossible under the old wave models. So you can obviously get them in any conditions. But you're not likely to get one that can sink a large container ship in otherwise calm seas (although it's not in theory impossible), which is what I was talking about if you go back to my original comment. The height is still proportional to the other waves.
I didn't see anything in the article that implied the rogue waves were proportional to the average. In fact the thing that makes them rogue is that they are many standard deviations away from the average.
This is not the first article I've read on the subject, it's my understanding that rogue waves are built from regular waves, therefore they're proportional - just many standard deviations away as you say. You can get a 20 meter wave in the midst of 10 meter waves, but you're not going to find that in 2 meter waves, rounded to an appropriate number of decimal places.
