I suppose it depends what she said. She could have a perfectly valid claim for PIP based on impairments to her lower body while being able to do physically demanding activities with her upper body.
The mobility part in particular was obsessed with “can you stand and walk X m” last time I had to help someone with their forms so if she’s claiming she needs to use a wheelchair to get around most of the time, gilded or not, she’d get her 12 points while what she is or isn’t able to do with her upper body or how much energy she has to do those things is entirely irrelevant for the mobility component.
Fishing's a whole body activity. That's my point - it's very demanding in a way that wouldn't convince an assessor that the participant needs HRM and/or HRC.