I just took a look at how Fat Larry’s Finance system is setup and it shows that the discount depends on if you have Intimidate or Persuasion of 5. If you do, then you can get the Finance bump regardless of your current Finance score. The reason Troika did it that way was because Fat Larry promises you a discount if you Intimidate or Persuade him, it’s not conditional like for Beckett, it’s certain you will get the discount. For this reason it has to remain how it is now.
So… if you have Persuade or Intimidate at 5 or higher, you get a FREE Finance bump.
(I would prefer it be conditional like for Beckett, but the way the dialogue is structured, Fat Larry promises the discount)