I don’t see a problem so long as they do so in good faith - for example publishing full event contents to ActivityPub instead of adding a link back to the Facebook Threads app, which is basically what a lot of news sites do with their RSS feeds to get advertising money.
So long as they do that, it’s not really possible to do a rug-pull. There are far more Facebook users than Fediverse users after all, so it’s going to be advertising for the Fediverse for as long as this lasts and if users would like to remain part of it they’ll have to move to another server. That is, assuming it ends.
To answer the question though, I don’t care for microblogging personally and I don’t like Meta as a company so I won’t use it. I appreciate the scepticism but I feel optimistic.
And no mention of what happens to their API but knowing google it either goes away entirely or totally changes with significant rework required.
Related, the reason I no longer use any google API: https://steve-yegge.medium.com/dear-google-cloud-your-deprecation-policy-is-killing-you-ee7525dc05dc