As I have said before, I am not a fan of the type of commemoration employed by the State of Israel for Yom Ha'Shoah (and Yom Ha'Zikaron), by way of the siren and standing in silence. I respect it, as that is what is done, and that is what people are sensitive to, but I do not consider it a holy ceremony that must be observed by all. I have no problem with other people choosing to commemorate in other ways - as long as in public they are sensitive to the public sentiments and to the public ceremony.

There are various excuses offered as to why some do not commemorate Yom Ha'Shoah.

I don't ascribe any specific holiness to the date chosen. Yom Ha'Shoah was chosen to be commemorated on the anniversary of the Warsaw Ghetto uprising. But in reality, the Holocaust spanned from about 1939 until 1945 - any one of hundreds of other days, outside of the month of Nissan, could easily have been selected as the commemoration date.

Is it being in the month of Nissan, a period of no mourning, really the reason some people refuse to commemorate Yom Ha'Shoah? Well, we take on all the customs of mourning during these days of Sefirat Ha'Omer, despite it being Nissan. We do not shave or get haircuts. We do not hold weddings. We do not listen to music (though there does not really seem to be a source for this). We say Av HaRachamim in davening on Shabbos, even on Shabbos Mevorchin and even if there would be a bris in shul. So we take on plenty customs of mourning during Nissan, just some won't take on Yom Ha'Shoah.

Regarding the date, it is true that alternate dates were suggested, and alternate dates have been declared as days of remembering the fallen in the Holocaust. Specifically the 9th of Av and the 10th of Teves. But let's be honest - have you ever seen a Holocaust commemoration on the 10th of Teves? Even if you have sene it in a community here or there, how widespread is it? On the 9th of Av we have a couple of kinot that have been published by some rabbonim. These kinot are said in many shuls, but beyond the one or two kinnot (that are mostly not understood by most people, just like most of the kinnot) there is no other mention or focus on the Holocaust. So, saying the other days are already commemorating the Holocaust is also just an excuse.  .

If the real reasons for refusing to commemorate Yom Ha'Shoah were religious in nature, then what is the excuse for not commemorating Yom Ha'Zikaron.

I believe in calling a spade a spade. Stop making excuses and just say it straight out. Some people choose to not commemorate the Holocaust simply because it is the date chosen by the State of Israel. Had the State chosen a different date, that date too would not be commemorated.

And I have no problem with that.

If some people want to say they have their own way of commemorating, on their own day even, that is fine by me. But let's just be honest about it, and not make up excuses.

The same is true of Yom Ha'Zikaron. If you do not commemorate the day for the fallen soldiers, do you do it on a different day? Do you express your gratitude and solidarity in a different way or on a different day? Do you remember their sacrifice in a different way or no a different day, or do you never do it at all? Do you dedicate a shiur to their memory, do you say a prayer for their memory? Do you plant a tree, build a shul, dedicate a school, complete a cycle of mishnayos, dedicate a memorial or do something else in their honor?

And, of course, at least in public having your own day and method of commemoration does not preclude being sensitive to the public sentiments on the publicly mandated day.