I'm coming up to speed on this issue now and have discussed this with Jamie Bennett, the security team and various stakeholders to unblock this MIR. The security team will prioritize this MIR for 18.10. Assuming it passing review, I would encourage the Ubuntu Desktop team to SRU this back to at least 18.04 LTS so users can benefit from the sandboxing feature.
I'm coming up to speed on this issue now and have discussed this with Jamie Bennett, the security team and various stakeholders to unblock this MIR. The security team will prioritize this MIR for 18.10. Assuming it passing review, I would encourage the Ubuntu Desktop team to SRU this back to at least 18.04 LTS so users can benefit from the sandboxing feature.