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Almost certainly, but throw a toe strap between the tombstone of the rack and your the headtube if you're likely to overload the rack, will forget to check the bolts occasionally or just generally like to play it safe.
As @Skülly said, multiple mounting points will be better if the bolt did come loose rather than doubling up on the midfork eyelet. That said, if the bolt does go, your mudguard will be in the wheel too so who knows.
Crown question like is the bolt designed for some plastic mudguards robust enough for 5kg