Can a PhD student accused of plagiarism revise/resubmit the thesis? I don't know how to ask this so please forgive my ignorance and lack of vocabulary. Consider a case as below. I just would like to know.. :

Can a PhD student who just defended their thesis, but is accused of plagiarism the day after that by his own advisor, be denied the right to correct/revise/resubmit/etc. the PhD thesis?  

I think it's unfair that the student is denied the opportunity to correct/revise/resubmit/etc. with the reason being "there's no time". Long story short, the part covered by the accusation is only related to the explanation of some previous research (with difficulty in English) and the result of the defense was Successful. At least the advisor (and we generally as people in academic world) should help - at least give him/her a chance/right of resubmission/etc., not denying the student's hard work, worth and right. Many other people got the chance to at least resubmit/redefend/etc. 

Any advice on what can be done also is very much appreciated.

[ADDITIONAL QUESTION]: 

On this page, it's said that the Materials and Methods part is often given a high similarity score in plagiarism checker software. What I understand from the link is, a situation like this is acceptable; not considered as plagiarism. I wonder if this is also true for other/most universities/institutions?
I think it's relevant what kind of plagiarism this is. 

If it's serious plagiarism, such as quoting large blocks of text without proper attribution, then that can be a serious academic offense. Asking why you can't just change it and re-submit is like asking why you can't just re-take an exam if you're caught cheating or why you can't just give the item back and forget everything if you're caught stealing.

Depending on your institutions procedures you might be allowed to resubmit if it's found that the plagiarism was minor, accidental or not actually plagiarism but I suspect you're missing the point. 

Plagiarism in a submitted thesis isn't like a simple technical error to be corrected, it's potential wrong-doing or dishonesty to be investigated.