Lol welcome to warframe, the victim gets the punishment here. DE is so staunchly against anyone taking advantage of their system that they'll screw over innocents far more than the abuse cases just to be safe, you see it as well with the prioritization of what gets fixed mechanically as well.
The only way you can be safe in this regard is to be insanely cautious while trading anything moderately valuable and to wait weeks to actually use your platinum. You're just part of the product, your well being isn't really valued appropriately.