Without OgNasty's opinion we can't really know if what hacker1001101001/poochpocket did was against the rules of the campaign or not. It's not that I'm "keen on exact wording", it's just that poor wording in this case doesn't really make the intent as clear as you claimed.
Then you or somebody else should ask him IMHO.
For me (emphasis) the intent is clear and I have acted accordingly.
Replace hacker1001101001/poochpocket with another set of alts in this scenario - would you still make the same claim?
I would hope so.
Remove all the other transgressions hacker1001101001/poochpocket is accused of from consideration - would you still red-trust/flag him for this signature application? If the answer is "no" then it probably doesn't matter much if at all.
Flag type 1? I am not sure there is consensus for this (given the non-clarity of the rule to others, and it being an attempted - yet failed(?) infiltration). So answer is no. [1]
Negative trust? Absolutely. [2]
[1] However, it would be simple in cases where the rule was clear and a full violation occurred (then I believe the campaign manager could use flag type 2 or maybe even type 3?).
[2] Negative trust was not weakened so that I would need stronger reasons to tag people after all.