There's nothing in the hosts.equiv(5), rshd(8), or options(1) man pages to suggest that telnet.hosts affects anything except telnet, or that rsh'ing

If you search for "telnet.hosts" on the NOW site, you'll find several online bugs related to this change in behaviour. The documentation can be found likewise, in an online "Changes to the System Administrator's Guide" for things that didn't make it into the Systems Administrator's Guide. The justification for the change was to provide more consistent access control (and "trusted.hosts" is an alias for "telnet.hosts", to help transition to the new meaning of the option).

As Bruce points out, per-protocol access control is desired, and we have someone actively working on that.

...Tim Thompson...Network Appliance, Inc...