Could the friend be a little insecure about her riding technique and/or skill? For me, if she feels that she needs all that equipment to "control" the gelding, that he's not a good match for her. Dressage horses are acutely trained... you cannot expect to pick up a pasture puff one day and say: "Now do as ____ did at the Olympics." Time. Training. Patience...
I have been in your shoes regarding this situation, and for me it did not end lightly. (On multiple occasions.) Suggest having your friend try riding without such a tight ensemble on the horse. How does he move? How does he respond? And sadly, there are such people in the world who don't have a clue what they're doing or what they want from their horse.... :/
"I'm no conformation expert, but I do believe that that cow just photobombed her. Twice."
"I don't know.......... looks more like a Quarterhorse to me."