That is a bit too skeptical.
If you do not have a bunch of weird transactions going on through your account (especially BIG ones), and you have legitimate, plausible or reasonable explanations for your transactions, and your source of cash and/or your identity verification, then sure they should want to keep you as a customer - otherwise you are correct, if you are raising scam and/or illegal red flags, they are going to have little tolerance for that (perhaps approaching zero tolerance, or at least the appearance of zero tolerance) because they do not want to get shut down and have their license taken away or to pay outrageous fines.
It's like some of the behavior of bar and club owners in the USA in the past 20 years or so, they have become very rigid about checking IDs to verify age because they do not want to have their liquor license taken away because they get caught serving liquor to a minor... so they have a zero tolerance policy and they are not very nice about it when they find someone in their establishment who is under aged. They can lose a lot of money if they lose their license.