First, insider trading makes markets more efficient and should not even be a crime. If there should be a crime then it should be applied to those in a position to wield the violence of the State to change financial outcomes but ironically in the US they are granted immunity.
Second, this has been a great example of subjective value theory and asymmetric information in action.
Third, unfortunately there is no way for Erik to 'take away this suspicion' because of the non-AML/KYC nature of the MPEx exchange. For example, he could of had a second or third or fourth, etc. account(s) that he used to buy shares with. It would be impossible for MPEx to determine whether the accounts were linked. Thus, it is impossible for Erik to either prove or disprove whether he bought any or a large amount of shares over the past month. It is what it is.
So at the end of the day it comes down to the application of the MPEx contract. In this case, it appears it was honored fairly. Sure, there can be some disagreements but under the business judgment rule I doubt any of them rise to the level of materiality. So just pick up your bitcoins and go forward. Bleeting like a stuck sheep is not helpful for your balance sheet.