@Sith -- that is good news.
You had the correct cable-modem (the older Hitron cable-modem cannot do "100-up").
You live in a region where "100-up" has been rolled-out.
Yes, it was bad for Shaw to offer "100-up" to "Internet 300", "internet 500", "Fibre+ 500", and "Fibre+ 750" customers, but not for "Internet 600" customers. Probably, nobody on this forum will be authorized to explain why that happened. Just accept it, and "move on".