It indeed hurts the hobby. Decisions like this give no one but Olaf the opportunity to inspect the code, or to improve the code. It locks people into his decisions, and also sets a precedent that proprietary software is somehow a good idea on the Amiga in 2016. Yes, one can and should certainly hold his own prerogative, but my point is simply that this model no longer benefits even the developer.
If Olaf is putting tons of work into Roadshow, developing it, supporting it, etc, then he can still do that when the source permissively licensed. If it's about having some trickle of money, then Olaf could for example setup a Patreon.com account. We'll all chip in some small amount on a monthly basis, and viola: Olaf is now a full-time free software programmer on the Amiga.
This is not the 1980s; we can certainly do better than some ancient vendor-style relationship with a developer.