1) WFBF (Want First Buy First)
2) UAL would likely fire a FA for just about any excuse (if they could - the union couldn't help on this one) so please appreciate that the FA likely thought long & hard about serving a first class meal to an economy passenger, especially in this particular instance with all the fuss & fury. It goes beyond wanting to help the young girl, despite whatever the mom was up to.
Also, the FA surely would have suspected that other pax might be recording his/her actions or planning on writing into customer service about (or tweeting) the extraneous meal service. No good deed goes unpunished. [Its not like when a nice FA slips you a warm chocolate chip cookie when you're sitting in the bulkhead on a red-eye where nobody else might notice - ahhh warm pre-merger memories]
There are probably active (or ex) crew members on this forum who can comment further on this.