The license states that it can be revoked if the licensee if found in
material breach of the terms. Microsoft's lawyers get to
determine that
No they don't, the phrase material breach has a very narrow legal
definition, it means that the licensee has to fail to keep an
undertaking made. Since the only undertaking made is not to sue
microsoft for infringement of a Sender ID patent there is absolutely
no ambiguity here.
and the only way to challenge and resolve that if it happens,
would be through the courts.
The only way to breach the terms of the license is to sue Microsoft
which means that you are already in court.