A safety based argument is a bit weak. There are schools and instructors who will push weather and there are those that won't.
The 150 hours required by doing the integrated course is a reduction of the original requirement for a CPL, so what is unreasonable about requiring continuity at an average rate of 10 hours per month?
My only concern with this new requirement would be if a student pilot got to the 14 month stage and within a few hours of completion then either became sick for a month or the weather went really bad in the last month.
There needs to be a process to allow extensions for special cases. Maybe there is?