Anything that helps should be used. People tend to blow this off but it doesn't just make a difference here, if they have something that they want to submit elsewhere, even to a contest, it makes a difference. Yes, they can run things through here or another writers site just to work it but why not do it right from the beginning?
I've helped out in and been a judge on a couple of contests. I've seen manuscripts get tossed because people wouldn't do proper formatting or the errors were so plentiful. I'm not talking about a comma wrong here or there, etc. I'm talking about multiple errors from page one of spacing, commas, semi-colons, apostrophes, etc. Essentially, the simpler things.
We had specific guidelines for submittal at my old job. There was a reason; with our format our directors and tech people could take one look at a script and know roughly how long it would be, how much time per page etc. We'd have submitters argue with us and say to get back to them and they'd do it after we accepted it. They never heard from us again.
In the case of your broken English speaker (good chuckle there)... no problem, been there done it. I've even had characters do massive, lengthy run on sentences. The only way I break them up it to have the character take a breath.