While Puppy may have found the fire stall decks to require being considered in every match, I found the same was true for speed rainbows. If your deck can't beat a speed rainbow, you probably shouldn't use it. At the moment, I'd say speed rainbows are more of a problem than fire stalls.
If you played in the upgraded metagame, you'd understand it ISN'T fine as is. But I'll add the choice anyway.
Obiviously rainbow is much more likely to be a problem than firestall. What I can see is majority are rainbow but not firestall in the metagame. Why prevent fire decks from using SoG but not rainbow? Because most of you are using rainbow decks and want to nerf other decks? It makes no sense.
Speedbows are another problem, but do indeed have more counters than fire stall depending on the build:
-Mono entropy (antimatters)
-Aether/Earth (sometimes; depends on build)
-Black hole decks
-Immo decks (sometimes; depends on build)
And can also be very vulnerable to bad draws. Granted, there aren't many, but I may be missing a few, and those decks are much better overall than the counters to fire stall.
However, you're mixing up normal rainbows with speedbows. Speedbows don't use SoG at all. The types of rainbows that use sogs aren't a problem at all.