The nether portal block is in the #hoglin_repellents tag, presumably due to hoglins being scared of entering the overworld as it would transform them into zombies. However, the portal block is not in the #piglin_repellents tag despite similar such events applying to piglins.

Whether this is a feature request or a genuine oversight is uncertain, as piglins indeed seem like the greater intellects who would know to fear portals as they end up transforming them into their zombified selves, which they do in fact run from.