Thanks for these @sapwood. 

Number 5 has included the source at the end of their article which is acceptable.  I've left a message with number 6 who will now be monitored.

I think that number 2 is harsh and do not feel that this warrants a warning - exclusion from this crypto academy task is sufficient in this case.

I'll monitor 3 and 4 before casting judgement.  Number 3's reasoning is plausible whereas number 4 is more suspicious purely on the basis of the repetitive argument - I find that this nature of argument tends to be a sign of wrong doing.