There is nothing wrong with leaving Mecca or even going beyond the Meeqaat as long as the mutamatti’ does not ‘return to his country, or go to as far as similar distance to his country away from Mecca.  This is the view of the Malikis. The Shafi’is and Hanbalis disagreed with that.  The jurists differed on this matter because there was no textual evidence, so it is subject to ijtihad. The majority of jurists opined that tamattu’ of Umrah to Hajj requires closeness of distance between them. On this basis, whoever leaves Mecca after the Umrah and travels on a journey in which prayer is shortened, then he is not on tamattu’.

Note that whoever wants to enter ihram for Hajj while he is on Hajj Tamattu, he is not obliged to return to the specified Meeqaat, rather Ihram from Mecca or the Haram will suffice and this is the basic principle.