They make it easy to spin up parallel agents. Managing them efficiently through a shared tmux instance isn't banned anywhere in the TOS, AFAIK. I'd worry more about it if I had to use multiple accounts or something using round-the-clock "automated" work flow. I'm using one account. Hell, the workflow I described, I am even actively logged in to my dev workstation with tmux and able to see and interact with each instance and "micro-manage" them myself, individually. The main benefit of this workflow is that I also have a single shared LLM instance that also has access to all the instances, together with me. I have plenty of other things to worry about besides a banned account from an efficient workflow I've set up.

just throwing out there that yesterday Boris (lead engineer for Claude code) literally told everyone on Twitter that the CC teams number one recommendation for users is that they should be kicking off multiple instances / agents in parallel. not sure if that's what you're referring to, but if so I'd be very surprised if they ban someone for heavy use of that workflow