In ICANN’s current registry and sponsorship contracts, the names of TLDs are reserved as SLDs. This practice may be intended to help avoid confusion (and to address an old security problem documented in RFC 1535). Additionally, names like dnso.museum or icann.aero are reserved. While these specific ones certainly have some merit, it seems like a gross exaggeration to hard-wire them into a sponsorship agreement.
Conclusion: The reservations may be one of those ICANN practices which should be subject to re-evaluation.