I picked up this lefty safari express stock for dirt cheap recently and I’m curious to hear the opinion of the experts here on suitability of the grain flow. It’s got some decent figure, but I’m not sure about the flow in the wrist. Seems more vertical than horizontal. I ordered several more of these stocks and will keep one assuming it will make a decent stock.

It was flat sawn, not quarter sawn; look at the bottom of the grip. So, there is no grain flow like you would see and want in a quarter sawn piece, where you want the grain not to cross the grip at too steep of an angle, making it weak. Yours is as strong as the wood itself because the growth rings are vertical (which is what makes it plain sawn)
Don't worry about it. Unless it is very soft wood and then it doesn't matter how the grain goes. But it looks fine.
Not an expert at anything.

I do have a degree in Forestry but this shows it better than I describe since I have forgotten all but two things about trees.

Thanks. That’s what I was thinking but not sure.

Is there any risk that the stock splits right down the middle along that vertical grain?

No guarantee that any wood stock won't break if it has not been properly bedded, and for hard kickers, install a barrel lug.
But, basically, no.

I wouldn't worry about that stock if its dryed and cured properly, I would be more concerned about warpage than breakage with that stock..Use a barrel lug and glass bed it, I like steel bed..Most factory stocks hold up under recoil as a matter of fact..at least up to 458 Win recoil..

Cross bolts, glassbed, extra recoil lug make for a great trouble free hunting rifle, even works on factory stocks.