The typesetter for the 1874 RLDS edition accidentally set are as were. Clearly, Moroni is referring to the current situation, as he does in the following verse when he refers to the possibility that Parhoron himself may be seeking power:
The present-tense are in verse 17 was restored to the RLDS text in 1908. The critical text will, of course, maintain the present-tense verb forms throughout the larger passage.
Summary: Retain in Alma 60:17 the original present-tense are in “those who are seeking for power and authority”.