Spamhaus block to much ipv4 blocks.
They just ignore small hostings and reject all official requests from data center.
If hosting offer shared or vps services they always may hammered by dumb spammers, but this not mean what someone should mark whole IP subnet as BAD.
IPv4 subnets already all reserved or sold, and replace it with new not possible (or not cheap) even for big hosting company.
There is no western based hostings who allow spam operations (for several years). All email spam now from botnets (home user pc's).
They should just make it legal to shoot spammers, botnet herders, virus writers and people like that.