MILB Draft Question

If a player that was drafted by a major league team in the current year and is ushered through the system and makes the major league team, is that player eligible to be picked up on waivers?

I know there is a rule in place that anyone drafted in the current year cannot be bid on, but what is the standard for players that make the major league team before the end of the year? Please provide citations to any rule that exists.

Thank you.

If he gets called up to start on a MLB team, he's a MLB player, & free to be added IMHO.