Because of the various issues here I again suggest you consult a real estate lawyer familiar with adverse possession law in your state. That bit of investment may help you avoid mistakes that could cause you to lose your adverse possession claim. You'll have just one shot at this; once the owner knows you're planning to take the property through adverse possession he'll eject you if the action fails and you'll not get an opportunity to fix the problems and try again. These things are very state law specific and to my knowledge no one here is a lawyer in your state that would know this stuff well enough to give you any firm assurance of what the rules are.
Not only is it not stealing, it is also not a low thing to do. The law is set up to try to promote economic use of property. This property owner has made no effort over the last 10 years to do anything with his property. Hasn't even bothered to eject the OP who has been getting a free ride from him over all those years. When the SOL period for the homeowner runs out (whether it is the 10 or 15 years) and he's done literally nothing with his property in that time despite being constructively on notice through the statute that he could lose it then he deserves to lose it. Property sitting unused and vacant is a blight in many cities. Best to get that property in the hands of someone who will make some productive use of it or, at the very least, will at least take the minimal steps needed to protect his own rights.
The problem here as I see it is that your defendant is not A now. It is B, who took the property by deed from A via the quit claim deed. B claims his title from A, not from the county. Thus, on the face of it, subsection (2) would not seem to apply to you. I've not researched the case law to see if that particular point has been specifically addressed.
The problem with this is that she is NOT your attorney and, moreover, it does not sound like she was addressing directly the situation of what SOL applies when the purchaser at a tax sale then turns around and conveys the property to someone else. If it turns out she was wrong, you'd have no recourse against her because she's not your lawyer and you cannot rely on what she told you as legal advice.

