The IDF has proclaimed a free-fire zone inside Gaza i.e. anyone who steps within (say) 500m of the fence can - and is - shot at by Israeli tanks. There is actually no reason whatsoever to accept at face value the IDF claim that this dude was "approaching the fence", let alone that he was armed.
UN: At least 1,332 Iraqis killed by violence in July (AP)
from the article: IDF kills armed Palestinian approaching Gaza border fence