This issue is addressed in many places on Wikipedia. The title of this article and all uses of the name within the article should be "Brian D. Foy", or even possible "Brian D Foy". The precedent has been set within WP:MOS-TM, and across many articles. Similar issues have been seen in the articles for The Pillows, Korn, or Firehose. When working with an English encyclopedia, you should use only English formatting for the benefit of all users. It may be useful to make a note of the stylisation of the name as seen on Korn. The article could begin something like this; 

 :Brian D. Foy (generally typset as brian d foy) is a... 

 For further examples of policies and similar disputes, see this, this, or this. Note that the last link explicitly states follow standard English text formatting and capitalization rules, which would include capitalising proper nouns (an elementary English concept, as anyone could tell you) and punctuation for "D", as it is an abbreviation (not to be confused with an acronym, not always requiring punctution, see AIDS). If the issue is not settled soon, it could be taken to the administrators' notice board, where it would be immediately corrected.  ''''