The converter's "collateral price" in this case is already a 3.5 day median. So it's presumably a reasonable price, unless you're concerned about the price of Hive being persistently pumped over a 3.5 day interval.

At 2x collateral, the converter already has to deal with being exposed to a price 2x his "expected" price (i.e. the median price at the time of the transfer), so it kind of feels like enough risk to me.

And a minimum over a 3.5 day period, or even a 24 hour period could potentially be very low, especially if there was one malicious witness feeding a low price. A single witness could effectively negate use of the conversion mechanism in this case.