* the neutrality isn't "newfound", they have it since the Vienna Congress 1814/1815
* back then the big powers of Europe feared that Switzerland will join one of their opponents, so it was dictated to Switzerland originally
* but later, when Switzerland saw how the countries surrounding them got demolished again and again in each war, they actually adopted it. It is now in their constitution, article 185.
* Switzerland is a direct democracy. The constitution cannot be changed by the government. And not even by the parliament. Only a public vote of all the electorate can change it.
* the swiss electorate is about 6 million people large
* the swiss banking sector only employs about 89'000 people
So, what can we learn from this? Your postulation is, in all likelihood, wrong. Why would normal people, like Carpenters, Farmers, Teachers, Nurses vote for neutrality to "appease certain Russians" ? They have no benefit from this.
Also, Switzerland isn't the only (current) neutral country in Europe. We have Austria, Ireland and some smaller ones, like Liechtenstein. We used to have also Portugal, Sweden or Belgium there --- is any of these current or previously neutral countries linked with money laundering? I don't think so. Therefore we can even dismiss that somehow money laundering is linked to neutrality.
If anything, then something else in the swiss law system is responsible: their banking secret laws. One can still open an anonymous "number account" at swiss banks. It's not cheap, but that is just one more reason why it attracts tax evaders and criminals.
And finally, that today Switzerland is specially linked to Oligarchs needs a proof. Why? Simply because Switzerland implemented all of the nine sanction packets of the EU. Despite not being in the EU. So Switzerland, like any other EU country, sanctions the Russian state, certain russian companies, certain russian individuals. Including some people one would classify as "Oligarch". All of them? Probably not. But then again ... this would be a problem of the EU, by not adding them to the sanction lists yet.