What constitutes good cause to excuse a petitioner's failure to first exhaust his state remedies?

"There is little authority on what constitutes good cause to excuse a petitioner's failure to exhaust." Blake v. Baker, 745 F.3d 977, 980 (9th Cir. 2014). But the outer limits are well-established. "While a bald assertion cannot amount to a showing of good cause, a reasonable excuse, supported by evidence to justify a petitioner's failure to exhaust, will." Id. at 982.

Aguon goes beyond bald assertions, offering specific reasons for failing to first exhaust his state court remedies:

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