you're missing the point. How can he almost kill vader when in the movie we see him get his butt handed to him by Luke (who wasn't really a jedi) and a blind Han Solo.
To add to this, Vader had him on the ground and at his mercy twice. Why wouldn't he just force crush his entire body and take what he wanted?
Vader could have just simply killed Boba without damaging the casket and took what he wanted. Again the comic was
PIS= Plot Induced Stupidity, the only thing that saved Boba was the casket...well that and he had to appear in EBS/ROTJ.
WIS= Writer Induced Stupidity, because clearly the writer of the said comic just wanted to make Boba seem like some BA
CIS= Character Induced Stupidity, this is clearly on Vader because he should have just crushed Boba and take what he wanted.