You wrote in OP

I can’t get over how facile and stupid the identification of LM was at a McDoballs. This is someone who fell off the entire grid for three months??

That directly juxtaposes the seemingly easy identification with an implication/presumption/insinuation/allegation that authorities were unable to find someone for 3 months. Since they were not looking, the original statement as such is pointless.

And how is that relevant to the authorities “not being able to find” someone when they are not looking for that person? oO

Three months? And no one correcting you on that? WTF? Couple of days between shooting and arrest…!

Other than that: yeah, unlikely anyone could recognize anyone from those pubished photos.