Gandhi is right.From my understanding just looking at it from the outside, it seems that by Trump NOT having a stated position on many issues (and thus being assumed to default to the general stance of "his" party) he's much closer to the core of the Republican party than Cruz is, which makes the idea that the parties important members will side with Cruz to stand against Trump because...reasons...all the more confusing.
Maybe I am 100% wrong on this, but I cannot see how Cruz can be considered the "Establishment" candidate, and if the political landscape inside the Republican party has shifted to where Ted Cruz is the "moderate" choice, I'm struggling to find ways that Trump is more extreme.
The Republicans might detest Cruz, but they loathe Trump. Cruz is more controllable than Trump (and his wife is a managing director at Goldman Sachs). Even after years of being shunned by the Republican party, Cruz is now getting a ton of support from the anti-Trump elements of the GOP.