Imho "lashing out" is Fe related but not necessarily Fe-ego or Fe-valuing related.
Several type descriptions pay attention to the fact that Reinin negativity associated with poor control of Fe can lead to "lashing out".
For example:
"Some ILIs have very poor control over their emotions, and may lash out angrily if provoked.".
"Although ESTjs may appear in control of their emotions they periodically allow flashes of fury to break through."