Twitter doesn't have organic speech, period. And now they're justifying why they allow some political ads, but not others.
I don't think a system that favors people based on how much money they have access to is great, but I also don't think a system that elects people based on their fame is great. Having both paid and unpaid options for reach provides a little bit more balance.
Proper enforcement is hard. They won't get there soon. It'll come slowly for a few years to avoid mistakes. When AIs get reliable at detecting lies/harassment, enforcement will become the norm. (my prediction)
If that organic component is bad like The Rock running terminator style, that may be very obvious given there isn't an astroturf campaign to keep that bad organic support alive.
And it is not independent / non-zero sum. If "A" gets more influence, it may take from "B"'s opportunity. And if the growth function is indeed super-linear, then B's opportunity is very quickly squashed.
What matters when running for an elected office is visibility and recognition. This recognition and unpaid organic reach may have not been what won Trump the US Presidency, but there is little doubt it won him the republican primary.