Except it was Cruz's idol, Trump, and the rest of the GQP that completely ignored the Khashoggi murder.

Yes, but he obviously is being the "tough guy," and ratcheting it up into a full-blown confrontation.
That's the Republican way: rattle the swords, ruffle feathers, confront, pick a fight, to score political points.
Talking behind the scenes to defuse the situation, and avoid public pissing contests, isn't their style.
Typical is Trump spreading the lie the Chinese invented covid-19 and deliberately released it into the world.
Why? To embarrass the Chinese and destabilize the regime.
That's not the way to maintain good relations with a regime which, like it or not, isn't going anywhere and, if enraged, can do a lot of damage to our interests in the region.

A no duh issue which, I would not be surprised to see Cruz fuck up somehow, at some point, and blame the liberal media for him doing so.
The Chinese are a repressive regime that doesn't want bad publicity from anyone for any reason, thus they will even stifle victims' voices. (Even crimes that every day Chinese would be put to death for committing).