Earlier quoted context omitted.
It sounds like they are facing a novel denial of service attack that was near to the point of being able to imperil their service. This is an obviously temporary remediation to keep the systems up, not a new policy for the site. And all of that falls right under the purview of the CTO.
They are, but it's self-inflicted: https://sfba.social/@sysop408/110639474671754723 > Lest anyone doubt that Twitter was idiotic enough to release code that would cause a race condition and result in its own users executing a DDOS attack on it, here's the network console readout from Firefox showing all the network requests blasting away.
Edit: looks like they fixed that issue with a login screen and no 10 requests per second issue. rats