Maybe I follow the news and things posted on DU too closely, but this was extensively discussed days ago when the threat was made:

Link to tweet

Do you see where Trump says "Watch father-in-law"? That is a direct callout with some context behind it, as discussed in the article linked below.

That IS THE THREAT.

Google: Cohen father in law threat "witness tampering"

https://www.huffingtonpost.com/entry/michael-cohen-trump-mafioso-don-intimidation_us_5c4261b9e4b0a8dbe17164e9

Davis later told MSNBC that the comments were a “definition of witness tampering and intimidation, and could be obstruction of justice.”

I don't understand the point of "Cohen should tell us" what Trump posted on Twitter for everyone to see with their own two eyes.

Doesn't this destroy Trump's claim that Cohen is a liar

Ummm... Cohen has pled guilty to lying to Congress. The thing is, he was lying on behalf of Trump. Please read this analysis if you are confused about what Cohen lied about and why:

https://www.democraticunderground.com/100211715561

...do we have a mob-boss for our President?

" “definition of witness tampering and intimidation, and could be obstruction of justice.” "

...when is our Congress going to stop being derelict when it comes to it's duty and remove this MAGA criminal from office?

...for what are they waiting, millions of dead people?

...

his family and his life - not just that of his father-in-law. The report I heard said Trump and Giuliani threatened him. That is why I got the impression that Cohen might have been threatened beyond Trump's tweet the other day.

Again a threat made by Trump is to me - a sign of his guilt.

I know that it is absurd that Trump is calling Cohen a liar - when it was Trump that ordered him to lie.

So I ask the question again - what is it that Trump is afraid that Cohen might divulge if he appears before the committee?

That is why I said - when Trump threatens Cohen - because he is afraid of what Cohen might reveal - Cohen in my mind was just made more credible by Trump.

It's my own weird kind of logic here.

IMHO that is extremely unlikely. Giuliani spent years prosecuting mafiosi, and even Trump is not so dumb as to make a direct private threat. It is a certainty that Cohen and his communications are all wired.

The thing about the father in law has been talked about for days as a nearly explicit threat constituting witness tampering.

Cohen making this claim in response may also be a deliberate, but not entirely unreasonable attempt by Cohen to help nail this thing down as witness tampering.

Giuliani’s prosecution of the Italian mob was quite good. And it created enough of an organized crime vacuum for the newer Russian emigré mobsters to establish and expand their foothold in New York and its surrounds.