A statement such as "We believe the exclusion of the "feds" this year does the exact opposite at a critical time." is just ridiculous. Even more bizarre is the idea of mentioning openness in the (current) government context.
If there is a positive effect between the openness of the hacker community and the Feds then why did we end up with the current situation?
The current situation is incredibly bad so I absolutely support the decision by DEF CON. Even if there is only one single occasion where people stop talking/avoiding a person who is working to close with government agencies this is a success.
People who work for these agencies will always hide behind some "greater good" narrative and avoid taking personal responsibility. My hope is that by getting personally shunned by their former peer group it might help them realize that this is not longer just business-as-usual.
Government loves to really up the public with the us vs them rhetoric so they definitely deserve a dose of their own medicine.