Bitcoin is a network that allows participants to hold and transfer value amongst each other. A journalist could use it to transact with sources, or perhaps to withhold their money from the grasp of an over-reaching government, but it will not protect a journalist that is publishing articles from an angry government.
A journalist could publish anonymously, and perhaps request support through bitcoin. In such a situation, the journalist may need to be careful they do not leak their identity, so they may have additional considerations in receiving the bitcoin (ie. being careful to not tie their identity to the received coins in any way).
Can the blockchain technology be used in a way to protect journalists from having to reveal the identities of their sources?
Bitcoin could allow the journalist and their sources to engage in pseudonymous transfers of value, but this is different than preventing the journalist from revealing sources. A technology like PGP encryption would be a much more appropriate way for a source to communicate sensitive information to the journalist.