He naturally hated the NAZIs and the German nation of the time, but he maintained a lifelong deeper distrust and probably-bigoted hatred for Poles (and Slavs from that part of the world in general) because it was Polish neighbours who put him in there, and he saw plenty of enthusiastic Polish accomplices.
Germans back in Germany or on the western front could often claim plausible ignorance of what the NAZIs were up to with the concentration camps. Volunteering in an SS militia in the lands where the bulk of the extermination of Jews was happening is another form of evil entirely.
The holocaust is the most horrible crime of the 20th century, probably of all of human history. Being an accomplice to it, even just in thoughts and ideology, is repugnant with no excuse.
Furthermore you are absolutely correct that Soviet rule was not something you'd wish for.
Waffen SS was however a truly heinous organisation. If you consider it common to join the SS I would state that it also paints a rather extreme picture of those persons.
I think it is very dangerous to apologise for SS "just because they killed Soviets".
You're thinking about SS units formed in Nazi Gerrmany-proper. Ethnic units, while technically a part of Waffen SS, were quite a different story. At least up here in between Nazis and Soviuets. Recruitment was mostly about defending from Soviets. In most cases leaders were well-known figures from interwar era. And usually those leaders did a lot to make sure their units ain't used for stuff you typically think of when you hear „Waffen SS“. At the end of the war, those units were the starting point for post-WW2 anti-soviet resistance. Both people and guns/ammo.
Buddy, think about what you are writing. You don't need to defend these people. What they did, what they were a part of, is in fact bad and they should feel bad.