Like you, I'd also rather Baam stay weaker. For me, it'd be to make his climb a lot more interesting (and keep his teammates relevant). But it seems SIU wants Baam to be at least comparable to the top 100 of the Tower at this point in the story. Baam eating an ancient High ranker fueled by the souls of thousands of rankers would push him into the top 50. At that point, it's hard to see how AA or Rak have any relevance to Baam's journey.
Absorbing White seems like the narrative end to this, but it's SO obvious that it makes me wonder if SIU is going to mix it up. Before this moment we had SIU repeatedly highlighting Baam's ability to break spells, so we could see White's spell damaged/broken--personally I'd find that much more interesting. We also have Koon, Cha, and Tan boi all trying to get to Baam's field, so we could see them interfere with this moment before the absorbtion. We also have a seemingly pointless High Ranker, Aria, literally just sitting on the field staring at this massive High Ranker clash. If White's instincts were worth jack, he should also be compelled to retreat.
If SIU lets Baam eat White, I guess he wants Baam to have a clash with someone huge.