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The employee would really have any options on these facts. Access to the employer's remote server can be cut off based on the fact that while yo are not FMLA, you are not supposed to be working. The employer may want there to be no question about them requiring you to still do 'work' while you are out.
So, it is not illegal for them to cut that access off. At least, it is not enough by itself to be any indications of illegal discrimination at this time. I would certainly make a record of it, but unless and until some other evidence of discrimination crops up, there isn't anything that you can use it for.