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"and since it is a tenka-ko, White must ignore any threat" - but the fact that White must ignore the threat is a sufficient condition for calling it a tenka-ko. So it looks to me that there is a logical inversion in this phrase, or at least a tautology.
Yes, there is a bit of a tautology there, isn't there? :)
The commentary from Go World (Autumn 1999 No 86, page 52) is:
White 214: The ko is tenka-ko, that is, so big that White has to ignore all ko threats. The successive moves of 213 and 215 give Black a very slight lead. Both sides play the endgame with precision.
As it turns out, Black wins the game despite losing the enormous ko fight.
Black wins by 1/2 point.