As a Marth player, I can attest that a lot of this guide is a bit more wishful than it is accurate. For one, I'd suggest stating at what percentages your "combos" connect. And secondly, up throw is a very poor choice for combos and should only be used to fish for kills at high percentages, I'll give you the down throw setups, but even then, most of those only work until about 50-60% at most. And a lot of Marth's air game isn't as laid out on paper as you make it out to be. Marth's air game comes from the player's ability to adapt to different situations. Is your opponent heavy enough that this move won't connect because they will fall out of its range? Is the opponent too small that my attack will barely whiff? Where will my tippers hit? Combos like these are never guaranteed because the cast of fighters is just so diverse, that there's no real way to pinpoint where each of your moves will hit perfectly. It's all about going along with the flow of battle.
I appreciate the effort, but I think this guide promotes really bad habits as opposed to providing good advice. Keep working on it!