You can't dump ballast fast enough to allow emergency surfacing systems to do their job.
It’s a very dangerous & utterly stupid situation. This is what they were doing for safety:
“The company claims this technology, developed in-house, uses acoustic sensors to listen for the tell-tale sounds of carbon fibers in the hull deteriorating to provide “early warning detection for the pilot with enough time to arrest the descent and safely return to surface.”
It was either somewhere in this article or another, that it was said carbon fiber hulls would ‘shatter’ when they fail - milliseconds of ‘warning’ is likely all they would get, if even that. Personally, I think that might be a more preferable end than crammed in a small space, total darkness, cold, condensation, running out of air - entombed alive for possibly hours/days before mercifully passing out from lack of air, then suffocating.
https://www.informationliberation.com/?id=63826