We had Phone Guardian and while on the one hand, it stopped Mr Microsoft from the sub continent , our daughters and our friends got very frustrated with trying to get through. Sometimes saying their name worked and sometimes it didn’t!
So after paw died I took an executive decision to discontinue it and I am now harassed on a daily basis by “Amazon Prime”, Energy saving companies , my bank (ostensibly) and even, yesterday, somebody claiming to be from a BT call blocking service. I was unconvinced.
So, on balance, if the rest of you can put up with the relatively minor inconvenience, I would say it is a good thing. They can get round it, by giving a name such as Fred or Bob and if your BIL knows à Fred or Bob he may inadvertently let them “through”.
My brother, normally a very technically and financially savvy man nearly lost £25k shortly after his wife died and he was just vulnerable. The bank refunded it but it totally destroyed his confidence at a very fragile point in his life.
Go for it.