I think it was more than just they didn't believe Elon had trouble raising the cash. They liked being in control of Twitter and getting easy money as board members, and didn't realise that they can get personally liable for billions of dollars of loss for shareholders and go to court for years if they don't at least consider the offer and seriously evaluate whether the offer is worth taking for Twitter shareholders or not.
> didn't realise that they can get personally liable for billions of dollars of loss for shareholders and go to court for years if they don't at least consider the offer
It is ludicrous to believe that, even if this were true BEFORE the Musk bid came in, they were not consulting with corporate counsel AFTER and in conjunction with issuing the poison pill.
As others have said, it is frequently used as a negotiating tactic and will usually pop up somewhere along the way in any unsolicited takeover situation. Just like the simple act of saying "no" is often a negotiating tactic and not a true statement of someone's unwavering intent.