I wouldn't blame the writers as they honestly didn't know about Owen.
Now whoever didn't clue them in that death references would be in bad taste - blame them.
Car commercial
Father: Son, here's all you need to know.
(pops trunk, revealing Christy's dead body)
Father: Son, can you say "Hemme"?
Son: Hemme!
Father: That's my boy.
Jericho: The name's...
(looks at tights)
...Y2J.
Mrs. McFly: Aye, what does it stand for?
Jericho: Ya...um...Yanni Jr. II
Mrs. McFly: Well it's a pleasure to meet you Mr. Yanni!