I have never considered the issue of being interventionist in terms of Jehovah’s actions with man. Clearly He has intervened - throwing Adam out, saving cain from death by others, flood, plague, fire so powerful as to raise even the trace of a city, Christ and the sacrifice. So yes, maybe He is interventionist. The only scripture I can point to is that “to whom He chooses He gives it”. Whether He does that outside of His purpose, is illustrated in Job’s case where prior to Job’s downfall, Jehovah had laid a ‘fence’ around him and Satan challenged Jehovah to take it all away from Job, and see if he did not curse him to His face. Jesus also intervenes in that he says that he is with the anointed until they meet again in the heavens, and I have no doubt, believing in equality, that man can be blessed for his loyalty and faith, prior to the new system. Equally, that we can be let go!