Mum asks for advice after mother-in-law walks around naked in front of kids

This is a bit of an unusual one.

A mum has taken to Mumsnet to ask for advice after her son told her that their granny was walking around naked in front of them. The mum explains that her mother-in-law had to mind them while on school holidays, and that is when the incident occured. She said:

"MIL had ds1 & ds2 for a few hours recently to help out with childcare in school holidays (not a regular arrangement). Ds1 came home and said gran was walking round naked! It turns out she had gone for a mid morning shower and was walking about naked (indoors obvs) "AIBU to think this is not acceptable, ds1 is 12 and ds2 is 7?"

Some mothers believed that the poster was being unreasonable. One wrote:

"What is your concern?? On the face of it I'd say YABU."

While another said:

"I can’t see a huge issue, to be honest."

However, other mums conveyed their shock at the situation:

"Oh come off it guys, 'what’s the OP’s concern?' How about it’s just plain weird! Especially a 12 year old, I wouldn’t be naked in front of my 12 year old so definitely wouldn’t be comfortable for my mother in law to be!"

What do you think about the situation?