Are you sure you're not making (potentially false) assumptions on their behalf?
Obviously I don't know them personally, but its pretty common for the family members of a suicide casualty to have emotional trauma from it for years to come. Its not uncommon for family members to have strong feelings of anger at the person who killed themselves.
The only time I have seen this, personally, was a friend who took his own life a few years back. Sadly he was only in his 40's, but he was extremely ill (my guess is that it was cancer). Whatever he had, it was terminal and he chose to end it himself. His family completely understood.
One typically makes those kinds of assumptions from one's own experience. Assuming non-dysfunctional relations. But who knows?
For me, its, thankfully, not my direct experience, but that of my wife. Her brother killed himself back in '97. There were apparently no signs (though I have my doubts on that based on what I know). To this day, my MIL still can't talk about it, my cousin-in-law spent years being convinced he was just on some clandestine military op (he was in the army), and everyone in the family seems convinced he was murdered rather (a couple of them are hard core in the conspiracy camp on this).
My wife seemed to have come to terms with it more than the others, but when we started having kids a few years ago, suddenly she only wanted one. Took some time (and a lot of fights) to get to the root of the problem. While she still won't admit it, its pretty obvious that one of the reasons she was opposed to a second child is that she didn't want our first daughter to ever suffer the same loss she did.
We did end up having a second child (just 3 weeks ago as a matter of fact!), but she still has, IMO, issues in regards to her brother's death.