sorry to contradict ‘sthicky guy” on his understanding of hallel pessach night. Please check shulchan aruch orach chaim,siman “tof pei zayin” (487) se’if “arbah” (four). the mechaber paskens that we do say hallen (with a brocho) both nights ( minhag hasfardim,obviously). On that, the remo writes : ” Vechol zeh, ein onu nohagim kein, ki ein onu omrim balailoh be-bais haknesset ha-hallel klal” – translation; ” we (the ashkenazim)do not have that custom ,as we do not say hallel at all in shul that night”.
Clearly, minhag ashkenaz is NOT to say hallel at night. The sefardim and- importantly- minhag Ho-ari is to say hallel (see Be’er heitev). This is why the Hassidim say it.
Whether there is a minhag “lo lifrosh min hatsibbur’ -not to stray from the people’s minyan- , I do not know. That said, the remarks of that very ungracious gentleman was clearly wrong and stupid.