lucas...the thing is now, that the system was filled and improperly bled from the start, that bubbles could be anywhere...and when you fill according to standard TIS instructions, there's no circulation of coolant.
The alternative method 'blows' out the bubbles where they should collect in the ET.
I don't think he can just pour coolant in now and fix his issue so easily...but maybe I'm wrong. Certainly wouldn't hurt for him to just add coolant and see what he ends up with...but usually the only time you'd fill to the top of filler neck is when you've drained the entire system and are slowly adding coolant...waiting for it to come out the bleeder. Now, I don't think it's that simple...but we'll see! lol