I partly agree with you on the merits, but please keep the inflammatory tone out. A moderation decision that you disagree with is not the same thing as “over-moderating”. Criticism is welcome but please keep it constructive.
The migration of your question from Super User is something that you need to take up on Super User meta, this community has nothing to do with it. Super User generally rejects recommendation questions (which is the primary reason why the Software Recommendation site exists in the first place), so your question was by no means “perfectly reasonable” there. Rather than being closed in place, your question was migrated here where it is on-topic.
The fact that Super User is busier is no reason to ask off-topic questions there. In addition, attention isn't the same thing as positive attention; Software Recommendations has a quality policy which increases the chance that the answers that you'll get will be good.
On the duplication, I had already voiced my disagreement. Your question is about Windows and gives a special mention to Bitlocker, and doesn't care about Linux support. The question it was merged into specifically targets people who use both Windows and Linux. These are important differences. It's not just about Jeff Atwood's words (which aren't always wise), but also a general policy of this site — we don't close questions for being vaguely related, we close them for being actual duplicates (meaning that any reasonable answer to one would be a reasonable answer to the other).
Unfortunately, merging questions is hard to undo. However, in answer to your question, I would refer you to what I wrote here and elsewhere: use your system's native encryption software. You're already trusting the vendor of the operating system anyway. If you don't trust Microsoft, it's not just Bitlocker that you need to stop using, it's Windows. Using a third-party product only increases the number of people you need to trust.