concerned for a friend’s dog

i'm adding behavior as flair but the behavior i am concerned about is my friend's. i am dog sitting her dog this weekend, 1yr 2mos with mine, 11 mos and my boy is fully house trained and he walks around 5-6 times a day. i live in a studio apartment so it's really worrying that my friend who owns the 1yr 2mos old dog does not 1) want us walking her dog outside to potty. he is in a diaper and since getting to my place 5 hours ago, has already pooped twice, 2) also does not want us to walk her dog around inside spaces like ross or marshalls and would only want the dog to be carried or put in a cart. friend said that it's because her dog just showered and she doesn't want him getting dirty? 🙁 background of this dog is that he was from an abusive home and my friend took him in 6mos ago. he has so much energy that he would often have zoomies around place and would snap at / bully my dog 🙁 i am concerned that friend's dog is not getting the exercise he needs to let all the puppy energy out. and it would really be helpful for him to get a structure to grow out of his aggression.

please help – how do i tell this to my friend?