Is the journal indexing by SCOPUS meaningless?
Scopus is quality-curated, i.e. getting indexed by it is not meaningless. 

However, it is not as selective as the Science Citation Index, which remains the gold standard. 

Therefore you are better off publishing in a SCI-indexed journal if you can. Arguing with your professor is unlikely to be a good idea in any case - they have much more experience than you and will have a better idea where to send your manuscript.