Was Alekhine Unaware of the Noah's Ark Trap?

The Noah's Ark trap refers to the following tactic that can be found in lines of the Spanish. After, for example, 1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 d6 5. d4 b5 6. Bb3 Nxd4 7. Nxd4 exd4 8. Qxd4?



8... c5! 9. Qd5 Be6 10. Qc6+ Bd7 11. Qd5 c4 -+ traps the bishop.

Yet, in a footnote to Yates-Alekhine, NY 1924, Alekhine says {note: I'm converting the notation to algebraic} "...White, after 5.d4, must reckon with either choosing an immediate drawing line (5...b5 6.Bb3 Nxd4 7.Nxd4 exd4 8.Qxd4 c5 9.Qd5 Be6 10.Qc6+ Bd7 11.Qd5 Be6 = {instead of 11...c4!-GP}), or being forced to embark upon a doubtful sacrificial variation beginning with 8.c3".

My understanding was that the Noah's Ark Trap gets its name from its antiquity. Yet I see that even 6 years after Yates-Alekhine was played, Steiner used this line as White against Capablanca (unsuccessfully).

Were the masters at the time of the NY 1924 tournament actually unaware of this trap, or am I missing something?