"là" is not necessary to this sentence
"-là" is used to reflect the "that" vs "this" nuance and to give a particular emphasis to "that boy" vs any other boy.
For "this" you may find "ce garçon-ci", but it is not part of usual conversations.
However, not two sentences prior to this one, the translation did not include "-la"
yes, I agree, so that the word "garçon" does not sound as "suspended"
I agree, from what I've learn "ce" can be translated as either this or that. Maybe with the -là the sentence is clearer, but it whould be acceptable without it.