The writers could have changed it so that RF comes from the 22nd century not the 25th.
Did RF have a hidden agenda? Sure he did, he is a sociopathic liar and a killer that hates Barry. Granted he has slightly mellowed thanks to having had to help Barry survive, become the Flash and train him, but for reasons yet to be revealed he hates Barry.
If Barry saved his mom there would be a time storm yes, but would the storm start 15 years in the past where/when he saved her or would it start in the present? By all rights the time changes begin where the change was started so the time storm should manifest over Barry's old home and then expand from there and then proceed into the 22nd century since that is where RF states he comes from.
However given that Barry was time displaced, he would conceivably be able to still get back to the future but it should be an alternate one as shown in Back to the Future part 2. Biff gives the almanac to his past self and then returns to what is still his future, and suffers a combination of heart attack and temporal erasure as HE was being erased and changed and then the ripple effect would eventually catch up to that future time and change it all. Marty and Doc go back and end up in the alternate 1985 because the ripple changes have already reached that point in time, thus they need to go back to 1955 and stop the whole thing.