"Relocation packages don't always cover things like rental deposits"
What exactly is it meant for? If you're offered 12K to relocate, that means 12K to move. Renting a new place is an obvious requirement for moving, along with travel expenses and moving your household items.
Sure he should have researched everything before agreeing to the move, but I would think it was a safe assumption that relocation funds could be used to relocate.
What should not have been a surprise is being sacked for taking time off work while on a probationary period at a company like Oracle. They are a US corporate. There is no "time off" during your probationary period if you want to keep the job, regardless of whether it's your fault or theirs that you need the time off. It's not right, it's immoral and should be illegal - but it isn't. I guarantee they have a clause written into every job contract that allows them to dismiss you immediately if you miss work during the first 90 days of employment, which is enough to satisfy the law in most countries.
Working for US corporates comes with huge risk. It's only worth doing if you know exactly what you're getting into and have a backup plan for when it all goes south.