One of the current hot topics in Bible translation concerns whether it is appropriate to use third person singular masculine (he, his, him) for a generic reference (male and female). This is a recognition about how language changes, and how does communication in that language retain continuity while incorporating the changes. It is not easy.
I think it important to realize that our language is not by prescription (“You have to write this way!”) but by description (“This is how we are communicating”). So, some may lament that “he has always meant both genders, and still does!” The reality is that many today do not recognize “he” in that inclusive way. So what to do?
Some Bible translations continue the traditional use of “he” (NAS 95, RSV [RCC 2nd], etc.). The NRSV (New Revised Standard Version, 1989) was the first major translation to consciously change translation wording to move away from the use of “he” for generic use. Most often the change was to the plural (“they”). And one (Inclusive Language Bible with NRSV) removed all male language even in phrase such as “Son of God.”
Most English translations fit somewhere between these.
Notice that these five translation (of Psalm 1:1-2) show the differences in how they adjust to the changing linguistic environment. NAS maintains the use of “generic he”; ESV does as well, but includes the footnote to explain that it is generic. God’s Word makes the noun in v. 1 generic (“person”) but retains the “generic he” in v. 2. NIV 2011 offers a generic (“one”) in v. 1 and continues with the generic (“whose/who”) in v. 2. NRSV moves to the plural completely.
I think that the NIV 2011 makes the better choice in this instance. I have argued elsewhere that while the change to plural solves the gender specific issue, it changes the dynamics of the Psalm. Obviously this is an interpretive view, but the point seems to be that the one individual in v. 1 faces the multitudes, whether walking, sitting, etc. By changing to plural, the translation suggests that the plurality of the wicked is now matched by a plurality of the righteous. The Hebrew does not seem to support that view.
Interestingly, when the TNIV was introduced in 2005, it opted for the plural solution in Psalm 1. One of the suggestions I had made was to continue with the singular but use different words. NIV 2011 followed that suggestion (probably not because of me!). But I think in this one instance, the NIV 2011 is the best.