Well, it depends. If he had 2 unlawful entries into the US, he was not eligible for the 10 waiver Before he actually stayed outside the US for the entire 10 years. Then he can apply for permission to re-enter after being deported. The proposed waiver does not change the law AT ALL, USCIS/DHS may not change the law. They can alter the procedures, process but not the law only Congress can do that. So, if he was not legible for the waiver within the 10 years, he would still have to wait 2 more years, and he cannot use the proposed often discussed but not yet implemented "new procedures" which have not bee issued. If he had been eligible for the waiver for the last 10 years, yet chose to stay in Mexico for the last 8 years (unlikely, you would want him here) then yes, he can even apply now or wait until the rules are implemented. good luck.
No, he won't be eligible to file under the provisional waiver program, but you can file a new I-601, even if a previous application was denied. Of course chances are that you'll need to start with a new I-130.
Feel free to visit my website for information about I-601 waivers: www.tunitskylaw.com.
The information offered is general in nature and not meant to be relied upon as legal advice. Please consult an attorney prior to making legal decisions. Visit us at www.tunitskylaw.com. Contact us at 713.335.5505 or email at firstname.lastname@example.org. Veronica Tunitsky offers in-person, as well as telephone and email consultations.