Will Fraser: I know well, that it is essential to examine multiple theories, but in this case we not only have an "order of messages", but we also have information about when the messages were received.
And while investigating many possibilities are important the key is, if one theory can't explain some facts, the theory should be adjusted, and if it cannot be adjusted to match the known facts, the theory can be droped.
This is why I think incing, software problems, etc. can be discussed but bombs are unlikely.
Not only because lack of threat, lack of organizations taking responsibility, but also because all the security present at airports, etc.