Maybe he though Ttyl meant
'Talk tough you loser'
'Time-to take your life
or
'Take that you lesbo'
After seeing that he just thought:
"Well bloody golly well gosh how dare he, I'll have to strike first"?
I mean that or he's just a douche who enjoys ruining hard people's work? Like the same sort in Rainbow Six Siege that kills teammates and quits the match. Vile types.