If it is a client that is viewing it and has no idea about changing their Acrobat preferences, you can just add in an extra point somewhere on the vertical on the "I" shape using the pen tool in Illustrator or InDesign. Then re-export to PDF using usual settings. Having the extra point in the "I" shape fools the Acrobat renderer into thinking it isn't a rectangle shape and thus won't "enhance thin lines".
I am having a similar issue with illustrator.
In indesign and my pdf the images are perfect. However when i send the artwork to a digital printer. I get a pixelated effect around my artwork. (See images)