Some time back, a Mormon friend couldn't go to his own daughter's wedding in a Mormon temple ... because he was known to drink coffee.
After my father died, my mother married a Mormon.
He was a coffee drinker (as was she) but at their wedding reception they didn’t serve coffee because the local bishop might be in attendance.
Maybe your friend wasnt “Temple Worthy” (no Temple recommend?) either didn’t tithe at the appropriate rate; didn’t attempt Ward services; was married himself to a nonMormon, etc) rather than the “known coffee drinker” as the reason. My husband’s family is LDS and I know the types of issues I Iisted have been discussed by those who aren’t able to attend Temple weddings (including the bride or grooms parents).
The coffee didn’t have anything to do with it, it was because he was not temple worthy.
Only about 15% of mormons receive the classification “temple worthy”.
They’d never give him a temple recommend because he’d obviously fail it drinking coffee.