So Equius believes there's a rivalry between seadwellers and Highblooded landdwellers and had expressed dislike for Eridan, but later he referred to him as royalty and suggested he should be brought back to life? I'm kinda confused. Equius why.

There is actually a mutual distrust between landdweller and seadwellers. Equius refers to Eridan as royalty because Eridan is actually royalty. Equius suggested that he be revived because he reveres highbloods and takes the hemocaste very seriously.