It's certainly true that everyone has to draw their own line. I'm not so sanguine about my ability to predict and prevent future malfunctions and there's no shortage of Garands in the world. I wouldn't shoot that receiver in its present state. Risk/reward from my perspective doesn't justify it.
Of course, I don't shoot low numbered Springfields either, so there you go.
I was responding more to your original suggestion the op take the receiver to an A&P and have the crack dp inspected, then shoot it in the cracked state while monitoring the crack growth. Suggesting that course to a third party is somewhat different than analyzing your own level of acceptable risk and taking the plunge yourself.
In your later post, I think you tried to clarify that you were withdrawing your suggestion that the OP to follow this course of action. While I wouldn't presume to deter anyone from taking their own educated chances on this, I did feel uncomfortable seeing someone advise a third party to do so.