re: Is LSU considered a CFB Blue Blood?

Based on how the definition is suppose to be used no. Based on how the media and OP used the definition, yes.

If LSU was more consistent in winning they'd probably be an undeniable BB. Problem is they have seasons between that while winning, are not what a BB should be doing. Too many streaks of so so seasons then an amazing one. Closest claim to a BB was in Miles peak era.

You need to consistently be in title games, consistently win, be a powerhouse in recruiting, etc. LSU has most of the attributes a BB needs but is too inconsistent in the others. But yeah, modern definition they're a BB. Programs like Texas aren't BBs anymore. They lost their BB status with 15 years of mediocrity. There's really only a few true BBs to NCAA that fit the definition today.