Hi, thanks for submitting your question today. My name is***** have over 13 years of legal and consulting experience in this area. I’m happy to assist you with your question today. I'm sorry to hear about your job loss.
Unfortunately, Texas like most states is an employment at will state - meaning you can be disciplined or terminated for any reason that is not otherwise a violation of law. These exceptions are the civil rights protections (e.g., age, race, sex, religion), violations of public policy (e.g., fired for attending jury duty, for refusing to break the law, for reporting illegal activity by the employer (aka a "whistleblower violation"), or having some contractual right to a just cause employment (meaning the employer cannot terminate you without industrial due process - which basically insures a fair and accurate investigation and decision). Without any of these exceptions, courts find that the employer has a legitimate business right to operate its business however it sees fit and the court will not second-guess the employer. These policies and decisions may in fact be awful and clearly not fair or even make good business sense. However, they are not ultimately unlawful.
What the employer did here is not an exception to at will employment. Regardless of your being on probation, the employer could terminate you to hire someone back. It's unfortunate they made up this excuse to terminate you; probably feeling they needed a better answer than "we wanted the old guy back". But the termination is not illegal.
As a consequence the only potential remaining option that you can pursue would be to file for unemployment benefits and claim, quite rightly, that you were terminated 'without cause', and seek unemployment benefits. You would not be able to seek damages but you would be able to contest the termination as being ultimately invalid.