I mean, that is a fine origin for a particular tribe of atypical lizardfolk, but I generally think the MM should present "regular" versions of creatures first and foremost (and then maybe some variants to show GMs how to do that).See here (my emphasis):
But the choices WotC has made with this version have been baffling me for a while. I am still looking forward to the MM (it is what actually sold me on the revision at all).
ETA: I do look forward to the look on a player's face the first time they try and use Protection from Good and Evil against a lizardman, tho.