(Emphasis added.)
"Beyond a shadow of a doubt" is EXACTLY the language used during voir dire to indicate what the prosecution is NOT required to provide. "Reasonable doubt" is somewhat less than that, but the wording (at least in NY and CA where I have been a juror) is somewhat ambiguous and, to some extent, every jury has to decide what it means. If you believe what you posted and are honest when questioned, you would be excused from any jury.
We should keep in mind that a sizable majority of murder cases that go to trial do end in a conviction. In TX and CA, murder convictions are obtained in over 80% of trials (and those figures don't take into consideration cases where a conviction is achieved after a hung jury/mistrial in which the DA can use what s/he learned from the first trial). FL, unsurprisingly, only has a 59% conviction rate. (Don't get me started!)
With four, attractive, young, white people horribly slaughtered, most juries will be anxious to convict, which isn't to say they will ignore their sworn duty. It's really too early to worry, but given conviction rates we should be concerned that BK gets a fair trial!