Matilda, being a cleaning robot for the hotel should have a key to lock and unlock all rooms in the Hotel. That should/would include the complaints department. As stated before, Matilda could have easily lifted poetry from a guests room.
Qixa has been setting up Holo-porn in Hotel rooms, and had a fling with another staff member, so it is very possible for her to have very similar access to rooms as Matilda. Not to mention she is a part timer for HHGTTG and could very well have a grudge/jealousy issue toward the full time employees. Giving Qixa the benefit of the doubt that she isn't lying when she says she's a townie, it is very possible this could all be coincidence.
He then heard the rustling of paper as the being rummaged through some sort of container
What sort of container? Did anyone else find this odd? Its from the first hit.
As he shouldered his small pack
Danibot mentions bringing a pack, perhaps this is the container mentioned in the first hit. I don't recall anyone else having any sort of container on them. He is also a part time writer for HHGTTG and could easily have grudge/jealousy issues towards a full timer as well. Also, he has been asking around to go do jobs that are not appealing to most. Perhaps a staff member gave him a key so he could get to work? Slipping papers through a slot one at a time seems almost as fun as cleaning a toilet, eh?