The Nazis did not go straight to exterminating Jews en masse.
It built up over time, but the start was a vast raft of demonising language, blaming them (and socialists and communists and social democrats) for Germany's loss of World War I. The Wannsee Conference, at which the definite plan of extermination was apparently decided, did not happen until as late as 1942. In other words, nine years after the Nazis gained power and only three years before their collapse.
Adolf's original plan was to drive the Jews out by making their life intolerable by persecution. He would have been happy if they'd all emigrated to the US and UK (leaving their money behind of course) but the USA and UK were not 'open border' states and turned most refugees away. A later idea was to ship the Jews to Madagascar, but the war made it impossible as Germany did not enjoy the freedom of the seas. Had we made peace in 1940, that might well have happened.
I think it's quite reasonable, if you see stuff tending in that general direction, to draw comparisons. It's ludicrous to call that any form of 'holocaust denial'. In fact, it's the direct opposite. It's worrying (perhaps excessively) that the holocaust, or something like it, will come again. Now if you want to say such fears are grossly exaggerated and even absurd, you may have a point, but it's actually the extreme consciousness of the holocaust in people's minds that drives such fears. Again the direct opposite of holocaust denial.