A Romero motion applies when a person has a prior strike and the defense is requesting that the judge exercise their discretion to not impose the old strike for the purpose of sentencing on the new case.
Nobody here can (or should) advise you whether the current offer is a good one or not. The only person in that position is the attorney who actually represents your son. If you're losing confidence, that's not a good sign, but the question is why? And is your son? Sometimes, a face to face meeting to discuss the situation (keeping in mind that the attorney may not be able to discuss certain aspects of the case and they won't discuss anything with you unless your son consents) helps.
Depending on how old the arson conviction is, what your son has been doing between that conviction and the current case, etc. - those all factor in with the Romero motion.
If I read your question correctly, he's looking at a minimum of 9 years, but they're offering a year in county jail and probation??? It sounds as though somebody has already agreed to strike the strike for the purpose of sentencing and grant him probation. In effect, it sounds as though somebody has already made a Romero-type motion/request and it worked. I may be missing something in the way you're describing the offers and minimums/maximums, so don't rely on anything I've said here to base a decision on.
Bottom line - talk to his attorney.... at length.
The above answer is for general information only and is based on the information you posted. Every case is fact dependent, so to get a thorough analysis of your situation, you will need to consult face to face with an attorney licensed to practice in the jurisdiction where the incident took place. Do not conclusively rely on any information posted online when deciding what to do about your case.
First, there is no such thing a a Romero Act. Romero refers to a case [13 Cal.4th 497] where the California Supreme Court said that a trial court coud , in the interest of jusice, dismiss an allegation that a defendant had suffered a prior serious or violent conviction. The interest of justice concept does not mean that a judge can just dismiss the allegation to get to a specific sentence [People v. Williams 17 Cal.4th 148].
As Mr. Dane stated, there are a number of factors the court has to consider including the length of time since the "strike" conviction and other personal factors.
I also agree with Mr. Dane that no one on this forum can advise your son based on what you have provided. It is only one side of the picture. As probation is not an option if one has a strike and is convicted of a subsequent felony.
If you are questioning the attorney, I suggest , as did Mr. Dane, you have a conversation with him. I would add that you probably have time to see other counsel and obtain a second opinion.
Keep in mind thta there are differences in approach and personality. I tend to be a bit more aggressive than some of my colleagues and a little less aggressive than others.
The above is not intended as legal advice. The response does not constitute the creation of an attorney client relationship as this forum does not provide for a confidential communication.
A Romero motion only applies when your son is asking the judge to not impose the penalty based on the previous strike enhancement. Most call it "striking the strike". With the 365 offer a Romero motion is not appropriate, but rather is used when one is being sentenced to prison. No person on this website can tell you if your son is getting a good deal or a bad deal as we have not had an opportunity to view the entire case and the discovery. If you have lost confidence in your attorney, begin by discussing your feelings with your lawyer. If you are still unsatisfied, seek a 2nd opinion from a local criminal defense attorney. Good luck