This shouldn’t be too bad for him. In most games I’ve played based on this system, there are usually several work arounds:
Respec
Certain level ups that allow you to invest in stats
Very rare quest rewards that give a permanent stat boost
Equipment that can compensate for weakened stats
Temp buffs from spells and potions
Of course, our MC tried to strike up a conversation with a goblin horde, so these solutions might elude him fo a while