I don't care about suit or jeans, but another thing annoyed me last week on BNE-MEL: I was in 3F, another WP in 3D, and luckily 3E remained empty. On the other side of the aisle, same scenario: 3A and 3C occupied, 3B vacant.
Gentleman walks in as one of the last to board, spots empty 3B (lucky he didn't have is eye on 3E), and asks FA if he could sit there instead of [whatever his assigned seat was, he was in row 6 or further back]. No idea if he was WP or SG or something. Anyway, FA tells him to take his assigned seat for take-off but she would check with the cabin manager if he could relocate. I saw FA have the chat with the manager, don't know what the verdict was but it included a lot of head-shaking by the manager. FA then went to talk to the gentleman.
Fast-forward 15 mins: Up in the air, seat-belt signs go out, and voila, 30 seconds later, Mr. X politely asks lady in 3C to please let him through and take "his" seat in 3B. Lady in 3C was definitely looking at him a bit annoyed but didn't say anything nor consult crew, just let him proceed. Not sure what 3A's reaction was.
What would you make of such a situation? Had he tried to sit in 3B I would have called used the call button. WP perks are scare and rare on VA so I value this bit of extra space, it's occurring rare enough in row 3. I know there is no such thing as a WP shadow or I don't have any "rights" over the empty seat next to me, but such behaviour supported by the crew is simply annoying and not correct.
This kind of thing happens on all airlines.
If you pressed the call button, you may or may not have a hard time actually asking the FA to make the culprit move, let alone the time and grief involved between the culprit, the FA and yourself. The culprit likely doesn't understand that row 3 is "Platinum territory" (and even then, this is a rather "soft" definition - there is no hard definition in any T&Cs, and certainly the seating of non-Platinum passengers in row 3 is not against the rules, unlike a passenger who tries to sit in Business Class when they are clearly not entitled in any way). The culprit is more likely to think you have a problem with him/her personally (i.e. the way they look, the way they are, "just because", etc.), rather than actually due to the fact they have rapaciously procured the seat. On those grounds, the culprit is unlikely to move unless the FA enforces it on the grounds of following crew instructions (and would have a hard time trying to justify any detention once on the ground), or you spilled red wine on them.
Perhaps the only grounds that the FA could possibly move them on is by informing the culprit that row 3 is reserved for Velocity Platinum guests. If the culprit then produces a Platinum (or Club) membership, could be awkward from there. Worst case is that they continue arguing the point (i.e. there is nothing in their ticket or website which states that Platinums only can sit in row 3, or they argue the "stupidity" of the rule). I'm not sure how strong the argument of "take your assigned seat" would be, except for take off and maybe landing (as safety/balance can be used to justify those grounds quite easily).
Overall, I am not doubting that Platinums are entitled to row 3 and a shadow is nice (and as you have pointed out, it is
not a benefit), but in the situation you describe, although we know what
should happen, the difference between what should and does happen is very disparate in cases like these. It's likely just as, if not more, frustrating for the FAs as it is for you.
There are a
lot of things that if passengers would just do what they are told to reasonably do (not unlike they would on the ground), air travel would be a whole lot more pleasant.