>>By Oct 15 he was in the hospital and after the doctor let him go home he needed some extra time to rest.<<
First of all, there should be little penalty anyway since it's based on balance due. Presumably a good faith estimate was paid with the extension request, so it may not even be worth the time and effort to request abatement.
Late Filing Penalty will not be imposed if the taxpayer can show that the failure was due to reasonable cause rather than to willful neglect. That is generally hard to prove, but medical incapacity MIGHT qualify if he can specifically document his condition and the time frame. The argument is much stronger when the taxpayer can claim an excellent history of compliance (including a good faith estimate with this year's extension), and/or describe SPECIFIC changes in circumstances to ensure the failure will not happen again. Taxpayer should sign the request, not you.
Quickfinder [stop screwing around and just get it] says, "Request abatement by submitting a written statement to the director of the service center where the return was filed. Include all facts showing reasonable cause for the failure and a signed declaration stating the following: [Reg 301.6651-1(c )]
"Under penalties of perjury, I declare that I have examined this statement and accompanying information and, to the best of my knowledge and belief, they are true, correct and complete."