It doesn't make sense for it to be illegal to forbid reverse engineering in a license agreement, where is that the case? If that is the legal environment anywhere, it would make more sense to just forbid closed source software. It would save a ton of time and effort and achieve the same goal.
And by the way, it has everything to do with open source. If the code was open, you wouldn't need to reverse engineer it. Every security analyst could just review the code directly and search for vulnerabilities. The whole disagreement stems from Oracle (and the author) deciding that they want protected, closed source because they view it as intellectual property, while some of their customers feel they can't depend on that software unless they verify it themselves. Well...you can't fully verify closed source software yourself.
It is really a very simple and fundamental disagreement on this one topic that creates the whole issue. It is completely valid to disagree with Oracle on this, and to tell Oracle you disagree with them. However, rather than violating their agreement, it would make more sense to decide to use an open source solution instead.