We also don't know for certain if that was him making the posts. The images he posted are from December last year. Multiple people have had access to that account over the years and someone could have easily made that post with or without his consent or involvement.
This is certainly a possibility, but the odds of some one else timing this so closely with his death seem pretty slim. Con artists also have some very distinct tells as well when they are running a con, and I didn't see any serious red flags in any of his postings. I do agree though it is probably a good idea to stop sending coins to his addresses though until it is absolutely verified his family has access.