You know guys who:
-Bump a thread from 3-4 years ago
-Sent tcs to someone before auction's end
-Report someone for nothing
-menace to Ban someone without permission or authorisation
etc... etc...

Well, to answer your question;
1) I agree that necrobumping threads is annoying, but an infraction would only be necessary if the culprit was repeatedly doing this.
2) Same as the above really; warn them first, then if there are multiple occasions where it happens then step in and do something about it.
3) In seriousness, if somebody cannot provide evidence to support their reason to report someone, then it was a waste of time and probably not worth the infraction, just a telling off.
4) I am not 100% sure as to what you meant by this one.

4. He means threaten to ban someone without any real threat I think.

#4 you know this is about guys who say "Offer below 20k will be reported/ banned" this is useless and show the bad mentality of the community

We already have an infraction system, which you know about. Infracting for the reasons you have given isn't exactly an improvement and would just stir up trouble rather than fixing anything. But the real reason we don't do it, is because it's retarded.