Arabic text has much higher entropy than English. The last two letters in the Arabic word he used (H M) is also the common suffix for "them". That's not strictly equivalent to simply "Morning!" in English.
Maybe the translation algorithm confused "Yisbah-hum" (good morning) with "Yitbah-hum" (Kill them)?
Note that in Arabic there are no vowels. Also note that it's not the common "good morning" (Sabah Al-khair), but a rarer term: one word, 6 letters, no vowels. The equivalent in english would be "gdmrng".
Maybe the translation algorithm confused "Yisbah-hum" (good morning) with "Yitbah-hum" (Kill them)?