I think technically they can. It’s because they’re downgrading them to a free service. I’m going to venture to say that it’s a money grab on a previously generous gift by slack.
does sound like it's causing issues that they don't want to deal with if it's not earning them money
> Slack, a Salesforce-owned workplace messaging app, recently blocked other software firms from searching or storing Slack messages, The Information reported on Tuesday, citing a public disclosure.
https://www.reuters.com/business/salesforce-blocks-ai-rivals...
It's win-win for them. Either they pay (they won't/can't), negotiate to pay ($$$ at least)- or they move away, all of which increase the amount of available resources for Salesforce.