I believe he's trying to say that Company Commands cannot take the Chapter Banner, as you've tried to do. They can take the Company Banner, which is not nearly as good.
The toughness bonus of a bike applies to all situations except for determining Instant Death. Furthermore, Bikes are okay in assault, and as they are Relentless, don't lose any shooting capability for assaulting. They're also pretty good at picking whether they want to engage in CC or not, and as T5 MEQs, they'll beat just about anything that's not a dedicated Assault unit.