When a notable person passes away, people are going to be curious about how. I understand that there are different opinions on what counts as "enough" information, but I've always thought that at least a brief allusion to "how" can deter worse speculation and intrusion.
A well-known travel blogger died suddenly last month, and until her family confirmed that it was probably due to an asthma attack, people were guessing overdose, suicide, drunk drowning, etc. There shouldn't be shame in how anyone dies, but keeping tight-lipped about the manner while sharing news of the passing is bound to invite speculation. Survivors can choose to share how ever much or little they like, but they can't stop human nature. Death is the great unknown and many of us assuage our trepidation by ruminating on the circumstances of others'.
"Found floating in the pool" is shocking and a bit more vivid than I was expecting, and probably not the Duggars' preferred phrasing, but it can also help explain the reactions they may be exhibiting. I agree with others who have said they give a wide berth to anyone for how they deal with grief. Just because many here don't like the family or hate their beliefs or lifestyle doesn't mean the Duggars are faking grief and didn't actually love Mary. They have a very different worldview from mainstream culture -- that's their whole schtick, after all -- but they are human beings and I'm almost positive they have souls. Yes, even Jim Bob! I've been pleasantly surprised to see so many comments giving them some grace on how they're reacting.