During instrument approach, is an abbreviated racetrack course reversal allowed?
Unless you were "cleared straight-in" for the approach, when IMOMY is your IAF (as it was in this case) you are required to fly the course reversal, even if you can execute a direct entry. This is because the approach does not have terminal arrival areas labeled NoPT. So, yes, it was appropriate to fly the 6nm reversal. 

That said, no, you cannot choose a different course reversal, even a shorter distance hold. When a hold is depicted in lieu of a procedure turn (HILO) you are required to fly the hold as shown. 

AIM 5-4-6 (4) states:


  If proceeding to an IAF with a published course reversal (procedure turn or hold­in­lieu of PT pattern), except when cleared for a straight in approach by ATC, the pilot must execute the procedure turn/hold­in­lieu of PT, and complete the approach. [emphasis mine]


The IFH that you cited in your question has similar wording:


  For a hold-in-lieu-of PT, the holding pattern direction must be flown as depicted [emphasis mine]


Occasionally ATC will act surprised or get frustrated with you for flying a reversal when you're within a 90° turn of the initial segment's course, but unless they specify straight in you're doing the right thing.