I'm not sure it's "spam" if you have to find it. Surely twitter ads are far closer to email spam than someone impersonating another person.
If you read the threads under certain people's tweets (or anyone's tweets containing cryptocurrency related keywords) you will have no choice but to wade through copious amounts of this muck.
Granted, I would consider 99% of what pg would likely consider "legitimate" cryptocurrency content to be de-facto spam, but that's just a part of being on the internet at this point. The problem he raises seems negligible in comparison to the other commercial content that pollutes twitter.