OK, there are two good reasons you should'nt make such a fuss:
1. We aren't sure if it's the same Whispering Death.
2. Hiccup is a tiny runt while Alvin is a massive dude. Maybe the dragon thought Alvin had more in comon with him, or maybe (even more likely) he thought Alvin would be a better meal if they get trapped somwhere with nothing to eat >:) (evil laugh).