The tag is present in Lintian version 2.104.234. That is the most recent version we know about.
All executables should be readable by any user. Since anyone can download the Debian package and obtain a copy of the executable, no security is gained by making the executable unreadable even for setuid binaries. If only members of a certain group may execute this file, remove execute permission for world, but leave read permission.
Refer to Debian Policy Manual section 10.9 for details.