Where is using the next highest category minimums not allowed? All you're doing is being more conservative, and in this case it's a necessity, because you're flying the approach faster.
Using the timing and tracks (which is what abc1 was referring to rather than minimums, I think) for a higher speed category is potentially an issue because of the greater effect of wind on an aircraft at a lower speed than intended by the procedure design. But if you're actually flying the approach faster, then of course you must use the procedure (timning, tracks and minimums) appropriate to the speed actually flown.