A lot of people have a bias against frozen meat - that includes frozen Mangalitsa.
One chef that knows a lot about Mangalitsa - Manfred Stockner of Zum Weissen Rauchfangkehrer - explained to me that as far as he's concerned, frozen Mangalitsa is just fine.
Coming from a perfectionist, that surprised me - but then he explained that because the meat is so fatty, it doesn't get damaged as much as you'd think from the freezing and the thawing. This sounds similar to the freezing of fatty fish versus the freezing of lean fish.
Wagyu beef, which like Mangalitsa, is very fatty, also performs well despite being frozen.
From a quality perspective, slaughtering and freezing Mangalitsa in the cold months, when they've got the best fat, can produce better Mangalitsa than slaughtering them in the hot months. I'd certainly choose previously-frozen acorn-finished Mangalitsa over fresh but grain finished Mangalitsa - a realistic set of choices, given the seasonal nature of the acorn crop.