Players of his or your level dont need openings
I heard this statement a lot of times, but still can't understand why. Why risk getting destroyed in first couple moves if you can do it yourself by memorising some lines?
Because if you just put most of your study time on openings you will reach a level - say 1400 for example... And then you will be +4 out of the opening and blunder it away 80% of the time.
That is a bad feeling... Because +4 out of the opening should translate to maybe 80% win rate, not 20% win rate... But if your opponents have better middle game skill and endgame skill than you - the game will be decided by them.
Also some opening study can be deep... Chessable (memorizing lines) is aimed at 2000+ players mostly... As a beginner/intermediate you need to work on understanding opening ideas and goals, exploring middle game patterns that arise from this opening- through analysis of your own slow games... from "just memorizing a couple of moves" mostly you get from that is reach positions that you are better but can't actually handle... Or a desire to memorize more and more moves to have that fake feeling of security across more of your repertoire...
I see this +4 from the opening as a safety barrier because if I blunder later I drop only to equality and can still win in the endgame
Teach him the opening principles and show him some openings such as the Italian, the scotch, the Spanish and so on. Then he can choose one to focus on ig