But if someone has
urgent work or any emergency and due to any reason unable to go for 1.5 month then it means application will refuse?
I cannot tell you because I do not know. No-one does, it seems. (Note, I don't fully understand your sentence above but doesn't really matter).
The problem in your question is assuming that there is a way to submit "reasons" and know in advance that they will be accepted (and often asked here "what happens if ...." as if there is some way to get the question/case reviewed during or after).
There is not (as far as I can tell). There are only some cases reported back either way (some refusals, some proceed with no issues).
What we know is: -IRCC relevant statute says PR-sponsors must be resident in Canada (no definition of 'resident' and no, wording does not overlap with or mean 'tax resident' ie. tax resident is not a guarantee; -IRCC regs do specifically say 'short trips' are okay (no definition); -enforcement of this is unclear.
All anyone here can tell you with some certainty is that going abroad for anything more than a short trip means a
risk that the application could be refused or delayed (and no way to know how long delay might be).
If you want to take that risk, it's up to you.
There are fairly often claims here that "I sent IRCC a note saying I had to go abroad because [reasons] and my application wasn't rejected, therefore all you have to do is provide a reason." This argument doesn't hold up - as noted, enforcement of this is uneven - and there is no
direct evidence that the "reasons" provided had anything to do with the fact the application wasn't rejected. It's the equivalent of me saying that sprinkling cumin on my balcony keeps tigers away because "see, no tigers!" Sure, maybe IRCC will read the note and be merciful - but no way to know in advance and hence no way to rely upon that argument.
[Side note for clarity: yes, a refusal could be appealed. But since the refusal/appeals process is quite long, it is
probably more effective and quicker to re-apply with the PR-sponsor remaining in Canada, or at least re-applying no worse than appealing. And if that is true, it means that the argument "you can always appeal..." or "I'll just sue" is dumb - since starting over was the default and suing/appealing gives you no advantage.]