I'm guessing you meant PADI, not PADO. Good for your instructor. PADI standards do not require it. PADI requires the swim/snorkel test be completed prior to certification.
There may be cases where you would like to delay the swimming test.
For example, where I work about 98% of people come into the course with at least 2 swimming diplomas. It's really not a question of whether or not they can swim. So when we can (when the weather is good enough) we delay the swimming until the Open Water sessions so we don't have to "waste" valuable swimming pool time on things we know they can do.
In other cases, obviously, you do it in the pool. The students I have right now hadn't been swimming in a long time and seemed intimidated by the swimming test. So I did it on Mod-1 and got it out of the way so it wasn't on their minds any more.
I've only ever seen a few people come for diving lessons who said they can't swim at all.... Those ones get an "intro" dive and a check to see how well, if at all, they can swim in order to see if it's even worth it for them to sign up for diving lessons.
The point here being that just stating that doing the swimming test first is best might *sound* great on the internet, but there are even better reasons to keep an open mind about when you put the test in.
Hence the freedom for the instructor to decide for themselves when it makes sense.
Oh.... and being a good swimmer doesn't predispose anyone to being a good diver. Some marginal swimmers are excellent divers and some marginal divers are excellent swimmers.
R..