Can a pastor remarry? Yes, if his wife has died.

Can a sister remarry? Yes, if her husband commits adultery.

Can a pastor whose wife has died get remarried with a sister who is already divorced with an adulterous husband? Yes!

The matter is simple. The other preaching coworker makes it complex.

He may be thinking about 1Timothy 3:2 (Now the overseer must be above reproach, the husband of but one wife, temperate, self-controlled, respectable, hospitable, able to teach ...). But he may have exegeted the requirement of "but one wife" wrong.

It actually means one wife as long as his wife is neither dead, nor adulterous, and remains legal married to him.

Do not put on unwarranted burden to people's shoulders.