Extra starting equipment not bought using starting gold

I have a player making a level 1 half-elf/half-dwarf blood hunter using the starting equipment packs who insists that his character can start out with 3 martial weapons (2 scimitars and a rapier) instead of the suggested 2 simple or 1 martial weapon.

However, the character has a sage background and all the abilities and starting gold associated with it. His argument is that as a blood hunter he can pick the two-weapon fighting style at level 2 and the character can afford it because he’s from a noble family, so it’s really not a big deal if he starts out with these weapons.

My concern is that the character is already pretty op with bonuses from being both an elf and a dwarf, but it’s hard to enforce any rules since I’m a new DM (this is my first game) and he has a lot of experience listening to D&D podcasts. When I suggested that he uses the gold he earns in-game to upgrade his equipment when he levels up, he said that people don’t buy non-magical items and this is the same as spellcasters not actually purchasing their components (I said that spellcasters can just assume they have the material components of spells in their component pouches unless there’s a specific cost associated with it).

Is it okay to allow him to have 3 martial weapons as his starting equipment? I’m fairly certain that he’s wrong about the not having to buy non-magical items part.