I concede that 'stereotyping' may be the wrong word here because there is some basis behind this based on religious documentation. Its more like 'guestimating'. I think it is entirely likely that Williams does not want to deal with family or church heat to a more liberal stance, than the other way around.Evert would (and has) told us.
With how outspoken Serena is on many / most current issues of social justice, her silence on this is strange.
Of course, I could have it exactly backwards. She may be quiet because her views are against the teachings of her religion. And if she reveals them, it could put her in conflict with her church (which is very important to her).
So your objection stands. My view is pure speculation.
With that said, I wouldn’t say what I’m doing is stereotyping. She says she’s Jehovahs Witness. And their beliefs are not secret. So it’s more than just stereotyping to assume she holds tso these beliefs if she is Jehovahs Witness.
But yes, I understand your point. Many Catholics aren’t against birth control for example, even if they don’t publicly say so. But I wouldn’t want to say that assuming someone agrees with the beliefs of their faith is stereotyping. That doesn’t seem like what the word means to me