Perhaps you should have doubt that older generation atheists are moderate, tolerant and reasonable, because religious zealots are not and were not the only ones who can make their intolerance, well, intolerable.
Not making it sound like all atheists are ornery (or oppress, persecute, and slaughter 'infidels' like the religious have), but given that the passion and enthusiasm levels of millenials have the depth and solidity of a selfie with yesterday's take out ramen, no.