Bolt broke In intake manifold? I think Bracket/brace protect tension bracket. GM doesn't spend a penny w/o a good reason.
Likely won't break right away.
Need to drill then use easy out.
Can use a long bit and drill thru trunk wall for access or maybe 90° drill and short bit to save you pulling intake.
the AL w/ propane torch to loosen the bolt. Shock the drilled bolt w/ "canned Air" upside down or Freeze-Off
try that a few cycle... warm Al, stock bolt, repeat.
If use lube than give time to work.
Warm means warm/hot to your hand only. More can damage the intake.
Avoid heating the bolt directly.