Nursing homes/hospices have banned all visitors, so it is just patients and nurses. When a patient dies, someone will clean his room of the deceased's personal belongings. My guess is someone from the hospice stole Bruno's phone when cleaning his room.
I seriously doubt this is what happened--starting back up with a post like the one that was made is a lot different than some random person finding a phone and, say, stealing bitcoin from a wallet or using the phone to pay for things via an app or something similar.
His password has not changed recently, which means someone either knows his password or has physical possession of a device he was logged into the forum with when he passed.
When he created a
thread asking for donations, he asked that donations be sent to
1FkHCFv8PN1kerJct3RsQQpMcRoTnx2vWe, and the coin in this address moved yesterday. The address the coin was sent to,
1MZh187t7Lkz3Zn5cpWFmQbqowfL6ReP29 received other transactions, presumably from various services that Bruno had coin on deposit with.
The transfer of coin means whoever has his phone at least knows what bitcoin is (many people do). I am pretty sure there are some people who work at nursing homes also have forum accounts at bitcointalk, and some others probably know what bitcointalk is. Even if whoever stole Brunos' phone hadn't heard of bitcointalk previously, s/he could have done some research.