I think he's totally innocent but I think he had a strong suspicion about what might have happened.
That was a lie. They had a shared Facebook which has been deleted and SP had a very busy Pinterest board with all that super controversial stuff about cultural differences.
It also apparently had a lot of stuff that I didn't look at at the time that caused some posters on here to think something sad was going on with her emotionally. I didn't look at it deeply but it was related as stuff about perfection and ultra thin bodies. I remember reacting at the time as, "Come on. Her Pinterest doesn't tell us a darn thing about why she is missing." One poster in particular was very sweet and delicate in their comments but found the Pinterest board to be sad and maybe indicative of something. They were probably right. She hadn't been found yet.
There was also a photobucket account and finally, there was a very public and very dramatic and detailed blog post SP had created about their "perfect" courtship and marriage. It can still be found within other people's blogs. It's pretty interesting. Especially when you match up the dates she lists for moving in and marrying KP with the dates of her prior marriage.
I don't know what happened here. I know she showed up with some intense I juries and apparent weight loss which supports her story. I alsonknow that:
1. KP and SP are very dramatic people.
2. The story and circumstances seems fantastical, doesn't fit any kidnapping scenarios and LE has been making statements or releasing info that either appears to not indicate a crime took place (FBI poster), or appears designed to insinuate things about SP such as inconsistencies in her recollection or a secret life she may have.
3. KP and SP are dishonest. They absolutely were into social media prior to the disappearance. And the marriage blog written by SP had clear lies in it about things in her life that we can determine were untrue simply by looking at public marriage records.
Of course none of this means she wasn't a victim. But it may have something to do with how she got there, why she got there and what she really went through.
I agree 100% with your conclusion, but not so much that saying they were private and not active on SM was (necessarily) a lie.
If someone asked me was I active on SM I would say no, even though I've been on (and off

On Twitter, just for example, I see folks who seem to spend their whole day there, tweeting & retweeting & seemingly trying to rack up as many tweets & followers as possible. I'm there almost entirely to "follow" peeps and orgs of interest to me, because their collective tweets provide updates & news I might otherwise not get, and they're all in one place.
As for their joint FB account. I never saw it, so don't know how they used that account, but as others have said, for many FB is a quasi-private place for families to share family photos & news. Settings can be used to disallow access by any other peeps, right?
All that said, what I've also seen often enough are folks who are all for using SM to their own advantage, but who complain about their privacy being invaded, etc. when the peeps whose attention they sought on SM " turn against them."
(One egregious example of that I remember well involved a couple who blogged about taking their toddlers on a round the world sailing trip, and who shopped their blog to local media and to multiple online groups.
Their blog was as personal as it gets, including details about the two having sex; the mother accusing her father of sexual abuse; and the same mother saying, frequently, that she wished the kids slept more often & longer so she didn't have to deal with them, and my favorite- an entry about her cooking a special treat just for her husband, lying to her kids when they asked about it, and hiding it until the kids slept & she and her husband devoured it by themselves.
Some readers of their blog found a lot of that pretty appalling, criticism they ignored, until......(long story short) one of their kids almost died on board, and the lot of them had to be plucked out of the ocean at great expense. Then the criticism poured in, which they responded to with great indignity, saying no one had a right to question their personal decisions or to invade their privacy).
It is also plain fact that after her return at least a few people supposedly close to the Papinis went all over SM to try to shape the narrative about what had happened. But... neither KP or SP have done so themselves, speaking in their own names. Their silence for the past year, actually, is IMO, one of the strongest arguments for believing that SP was indeed victimized, whatever the circumstances & motivation may have been.