okay, maybe it's connected to this dj...
http://www.mangago.me/read-manga/gintama_dj_ukatsuna_yakusoku_wa_suru_na/
SPOILER:
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that would explain their behaviour a little bit but it still doesn't answer why he would say gintoki would die ╮( ̄▽ ̄)╭
Have you read any other Gintama DJs of this author? You'll be saying 'Poor Hijikata' a thousand times over
What was that