Use of word "Japanese" makes complete sense as this is Memorial Day weekend. 

To say what the tweet said is boneheaded. Dumb. 
Reprimand him, fine. Make him apologize publicly, fine.  But to fire him? Wow. 
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Being PC has got to be very difficult in today's Day and Age-seems like everything is described racist, or offensive.  Somebody somewhere is upset over some 'slight' -

So pick our battles. Not sure this one is worth it? Don't we all have bigger fish to fry?