Seeing the premises of the picture - the rider has halted his horse and is talking to the woman - he might just be resting/stretching his legs. Why, I even have a picture of myself somewhere, doing the same during a clinic and naively hoping that nobody would notice.
However, when googling "Marwari horse riding" I did find quite a lot of pictures like these, however, they all seem attributed to traditional tack/riding style, nothing more contemporary like jumping, polo, or even simply trail riding. Might be a cultural thing, linked to the horses' way of going and the tack itself, and not something I see as practical and safe.
However, I find more of these:
As far as I see, stretching the leg forwards that much tips the pelvis backwards, shifting the core and the shoulders of the rider backwards in a diagonal line against the horses' spine, which must be creating a lot more uncomfortable pressure. Look, how noticeably inverted those first horses are going. Additionally, the riders hands in this position seem to be bound to brace, as his body is searching for balance.