That said, I would not be surprised or disappointed if NYT got this material from Trump's team. The way I see it, the "leak" is certainly not illegal or unethical, witnesses are free to talk about their interactions with investigators and grand juries. It's not a leak at all!
Also, the story and its aftermath will tend to benefit Trump. Looks like Mueller over-reaching, might rekindle the Mueller has a conflict in judging actions taken against his friend Comey so by DOJ regulations must recuse, and numerous other angles.
What bad grammar? Where are the mistakes in the Times report? I don't see any. For Zeldin to be correct the paper would have had to fix up errors when they published the article.
I do see some questionable usage of commas, but it's not something that lawyers or reporters absolutely would never do. And there's some "with whom." If Trump is so illiterate would he really know how to use "whom"?
But of course the idea that Trump himself would personally leak the questions isn't believable. If somebody else in the White House did leak the questions, why would they necessarily be less literate than Mueller's staff or the Times staffers?
This is the age of cut and paste. If you get the list of questions and want to pass it on, you can probably just cut and paste them from one document to another. So where do errors come into the picture?
And it's not just cut and paste for the recipient of the questions. It's cut and paste for the lawyers who drafted them, too. The questions weren't some great and eloquent work of art. It's "What did you think ... ," "Was the purpose of ...," "What was the purpose of ...," "What did you know ...," over and over again. If there are mistakes in grammar, it's probably because they had all those beginnings of questions and cut and pasted them with the second half of the question (the thing they were asking about).
So I don't think there's much credibility to the story.