Aluminium rigid fork for winter I'm looking for the bike for winter riding and found this one.

It's all good, except for the fork: some people say that aluminum rigid forks can not absorb vibration and therefore are bad for the winter 'cause there's firm snow and ice, which is not smooth at all.

So, are they right and I have to look for steel or carbon fork? (I'd really like to use rigid one for the winter)
Presumably you are looking for a cheap bike to ride in harsh winter conditions. The advertised price of 35,960₽ is about US $615 (at the time the question was asked) which would be considered a quite inexpensive bike here.

Your choice or tires is going to make a much bigger difference than a carbon fiber vs aluminum fork. An aluminium fork will be fine, but look for a bike with clearance for bigger tires.