What rank did your little brother have when he hit L28 & entered the Shard?
Back in April when I started I zoned in at about 7000, my friend did the same just under a week later & was at 16000 in the same shard. Also while I was L28, the shard leaders were already 50+.
So it looks like it was about 2 weeks to fill up.
L85 part is possible with the Hyperdrive Bundle.
Some of the characters are in the Bundle while others have Bundle Packs for just the character (Grievous, ARC, & Shak Ti)
I also think the G13 is possible given a few bundles I saw last month with G12 pieces in them.
So all total, I'm betting you could get those results for about $300-ish, maybe a bit more combined with say 3 weeks of farming nodes.
So yeah, its possible if unlikely.
PS. I am thinking Next Level Whale to be in the multiple 1000's spent. So I guess it depends on what you consider "Whale".