3.2.2.3.7 Topic Alias Maximum - simplify text for 0 and absent cases

Lines 1572-1573 seems to suggest that there is different behavior for a value of 0 versus an absent value:

"A value of 0 indicates that the Server does not accept any Topic Aliases on this connection. If Topic Alias Maximum is absent, the Client MUST NOT send any Topic Aliases on to the Server ..."

Is this simply one case where an absent value defaults to zero? Not sure why there's a distinction between "does not accept" and "MUST NOT send" in this sentence since Line 1571 already states:

"Client MUST NOT send a Topic Alias in a PUBLISH packet to the Server greater than this value"