Well to start with, option 2 seems a fairytale, if the guy settles before you that have capacity to rush catas early, he probably spent a s**tloads of gold to settle and it seems unlikely he will just quit after 3 weeks, sure something could have happened irl but the example really dont apply to the reality as a common behaviour.
Try to play Egyptian and you will see.
Option one: i believe that noone would be such a bad player and get a nice 15 cropper, but anyway i still believe mh investigation could lead to the solution.
Option 2: u can see that a well rounded 15 cropper without defence is going go be chiefed, so it's obvious that is a friendly chiefing and u ban the player.
Did I hear you right? You suggest that every chiefing that did not meet defense is friendly and bun the player? Which of two players btw?
1. Player is complete noob if you settle next to a 15c egy and they don't notice you "rushing" chiefs which would be *very* slow in the context of v2-v3.
2. MH could just implement a lesser penalty in the greater probability that its arranged chiefing without direct evidence, although such clues as speed of settling for both parties, is the player making def, does player B try to scout, etc - circumstantial evidence, or lack of defensive actions that points to arranged chiefing could be used in a "judgment call"
Will the probability table made public? How will you calculate it? And do I get it right - newbies should be penalized just because they are less experienced?