That line can only be seen on the Western/International version of the game. The original Japanese box art says "すべてが管理された世界で、レイヴンたちの戦いが始まる" which roughly translates to "In a world that is totally controlled, the Ravens' fight begins." It's the publisher's fault (Agetec), not From Software's. AC3 is officially a reboot, just like AC4.
Also, profanity doesn't mean a person is mad. I'm not defending R.Leonhardt or anything but I personally didn't see any indication that he was attacking you in any way. He came off strongly, but it was obvious he was trying to debate and gave the "From's word is final" argument. Lighten up.
EDIT: Edited the kana to reflect the actual text. I seem to have converted 'subete' and '-tachi' to kanji.
EDIT2: I just read the English text and I believe it is not a reference to the previous Armored Core but more of a backstory for the setting of the new series (although with similarities to what happened in the previous series which makes it confusing).
EDIT3: Or maybe it really was intentionally done by Agetec (or they mistakenly thought that AC2 and AC3 were connected) since it conflicts with the Japanese text.
Also, profanity doesn't mean a person is mad. I'm not defending R.Leonhardt or anything but I personally didn't see any indication that he was attacking you in any way. He came off strongly, but it was obvious he was trying to debate and gave the "From's word is final" argument. Lighten up.
EDIT: Edited the kana to reflect the actual text. I seem to have converted 'subete' and '-tachi' to kanji.
EDIT2: I just read the English text and I believe it is not a reference to the previous Armored Core but more of a backstory for the setting of the new series (although with similarities to what happened in the previous series which makes it confusing).
EDIT3: Or maybe it really was intentionally done by Agetec (or they mistakenly thought that AC2 and AC3 were connected) since it conflicts with the Japanese text.