a) There is no evidence of mass-scraping. b) It is legal and ethical to scrape public data. Especially when that data is owned by its users and not by Twitter.

a) There is no evidence of mass-scraping. b) It is legal and ethical to scrape public data. Especially when that data is owned by its users and not by Twitter. c) The more likely explanation for Twitter's rate limiting is that they didn't pay their AWS/Google bill and rather than cut the service off they limited its bandwidth and/or compute capacity.