Hello and welcome to JustAnswer.
I'm sorry to hear about your situation and hope I can help.
That definitely seems completely unfair and likely constitutes a breach of your contract. When 'suitable' is used in this sense in the contract, it would mean someone with the approximate level of skills and abilities as you have who is capable of performing the job in approximately the same manner.
Since it was your responsibility to find a replacement, it would be your contractor's responsibility to prove that the replacement you found and suggested was somehow unsuitable for the position. I find it hard that they couldn't find someone in the entire Bay Area (or at least California) who could fill in for you too and that they 'needed' to send someone from Lousiana.
Your legal recourse would be to sue in small claims court (Although any cost that you would have incurred in finding a replacement would likely be deducted from that recovery).
However, suing your contractor would likely mean that they would not look to use your services in the future, so despite the money being unfairly deducted from your pay, you may want to let it go if you plan on working for this contractor in the future.
If you don't plan on having any future working relationship with them then you should sue in small claims court, but otherwise, the future cost definitely outweighs the benefits of suing in court.