I'd be surprised if the MOT tester counted the frilly wing as structural, but standards and opinions vary.
Did your local welder prod the sill itself when he looked it it? It still looks to me like there's either a hole (or what would be a hole soon) in the area next to the wing edge, and another patch of crusting at the bottom seam - obviously I'm only looking at a picture, so not able to use touch, but I would expect my local MOT tester to at least comment on them (after failing the wing on sharp edges likely to cause injury...), but if they "creak" when pushed gently then I would expect a fail sheet.
If they're solid and it's just surface rust, a quick clean-up, but of rust protection and a squirt of paint along with the second hand wing should keep it on the road for now.
Word of warning about second hand wings - some people bend them when removing as they try to separate the seam sealer band that runs vertically. This makes them hard to fit well, and usually the reinforcement panel is loose. They can be "adjusted" to fit better.
Did your local welder prod the sill itself when he looked it it? It still looks to me like there's either a hole (or what would be a hole soon) in the area next to the wing edge, and another patch of crusting at the bottom seam - obviously I'm only looking at a picture, so not able to use touch, but I would expect my local MOT tester to at least comment on them (after failing the wing on sharp edges likely to cause injury...), but if they "creak" when pushed gently then I would expect a fail sheet.
If they're solid and it's just surface rust, a quick clean-up, but of rust protection and a squirt of paint along with the second hand wing should keep it on the road for now.
Word of warning about second hand wings - some people bend them when removing as they try to separate the seam sealer band that runs vertically. This makes them hard to fit well, and usually the reinforcement panel is loose. They can be "adjusted" to fit better.