"It's only a flesh wound..."

Seriously, I like Barry's suggestion ^. You can categorize the risk in riding this fork in the following way. Failure Mode: steerer tube breaks, leading to immediate loss of steering control. Severity of outcome: Catastrophic (highest among: catastrophic, critical, moderate, negligible). Likelihood of outcome: Medium (mid-range among: very high, high, medium, low, very low). A catastrophic/medium is a no-go without successful mediation, it cannot be simply accepted. Mediation in this case can be repair or replacement.

You see, the likelihood is the thing that we are struggling with. Is it medium? Is it high? An experienced carbon repair shop/facility can give you a better idea. I'm saying that it is likely to fail. But what do I know. If it were my fork, I'd replace it rather than repair it.