[josu]

As long as his Twitter account was isolated[1], the only risk was losing control of his twitter account for a few days. And given the fact that he published an article previously saying that he was going to give away his password, I don't think that he would run into much trouble even if they used his twitter account for malicious purposes.

[1]This is, the twitter account wasn't being used to log into other services.

[tempestn]

You assume that losing control of his twitter account couldn't have unforeseen consequences. I'm sure the author didn't expect that he would end up having to change his phone number. It's not at all implausible that there could have been further repercussions.