There are some positive aspects to the above paragraph. For one thing, it was the much delayed criticism of Abbas. Maybe Krauthammer's column forced their hand. And the editorial refers to the incident where seven teens were killed as an exchange of gunfire, rather than accept their reporter's effort to turn it into a one-sided affair.
However what is bothersome is how the editorial calls Abbas "a strong and courageous opponent of violence against Israel." He has condemned violence because he believes it to be counterproductive. That's not a strong condemnation. As Daniel Pipes noted "Mr. Abbas is not a moderate but a pragmatist." Pipes gives a fuller context:

The other problem is blaming the past decade's violence and tyranny exclusively on Arafat, and erroneously assuming that, now freed of him, the Palestinian Arabs are eager to reform. Mahmoud Abbas, the new leader, has indeed called for ending terrorism against Israel, but he did so for transparently tactical reasons (it is the wrong thing to do now), not for strategic reasons (it is permanently to be given up), much less for moral ones (it is inherently evil).

Later the Post's editorial asserts:

The new Palestinian leader, unlike Mr. Arafat, does seem to have a positive strategy. It is to co-opt secular and Islamist militants by persuading them to declare a unilateral cease-fire and participate in the Palestinian political system.

Arafat didn't try to co-opt Hamas? From the Washington Post January 23, 1996:

Others, such as northern Gaza's Emad Falouji, are members of opposition parties whom Arafat placed on Fatah slates in an effort to co-opt them into the council.

More explicitly from "U.S. ISSUES TERRORISM WARNING HAMAS AIDE'S SHIFT ON EXTRADITION CITED" (1/31/97) we have:

Arafat has asked in the past that Abu Marzook be transferred to an area under Palestinian self-rule, where Arafat has tried with some success to co-opt relative moderates in Hamas and to crush die-hard proponents of terror.

"U.S., ISRAEL FAULT ARAFAT ON HAMAS CLINTON, CIA REPORTEDLY WARNED AGAINST LENIENCE WITH FACTION" (3/24/1997):

Palestinian officials strongly denied all accusations of complicity in Friday's attack. They argued in interviews and diplomatic contacts that Arafat has sought -- at times with Israeli and American approval -- to divide and co-opt Islamic extremists by freeing those who submit to his authority and pledge to halt armed attacks on Israel.

(The above article was a whitewash attempting to separate Arafat from the Purim day terror attack at a cafe in Tel Aviv in 1997. Israel claimed that Arafat had given a "green light" to terror; the Washington Post faithfully making sure that Sec of State Albright's "we can't be sure" statement dominated the coverage.)
And another from 1997 "POLITICAL PERILS TEST ARAFAT'S SURVIVAL SKILLS
ISRAELIS WORRY ABOUT RISKS OF NETANYAHU'S SANCTIONS" (8/24/1997)

When Yasser Arafat kissed and embraced the leaders of Hamas and Islamic Jihad at a meeting of Palestinian factions this week, the conciliatory gestures toward radical Muslim groups suspected of perpetrating terrorist acts outraged much of Israel and the Western world.

Was the leader of the Palestinian Authority condoning violence against Israel and preparing for the kind of armed confrontation that has spilled so much blood in the Middle East between two peoples fighting over the same land? Or was he engaged in a clever ploy to co-opt the enemies of peace and thus strengthen his hand for future negotiations with the right-wing government of Prime Minister Binyamin Netanyahu?

In each of these cases the term "co-opt," used by a Washington Post reporter, was an excuse. It was an excuse for Arafat's inexcusable alliance with Hamas. So the Post's editorial shows how little the Post's editors pay attention to their own archives. Arafat was indeed co-opted Hamas. But it was always an excuse. Abbas co-opting Hamas is much the same thing. It's a way to excuse the inexcusable.
Now the editors of the Washington Post are using the term to moderate Mahmoud Abbas who has done nothing to earn the benefits of doubt that they wish to bestow upon him.
The Post's criticism of Abbas is, alas, too little and too late.
Crossposted on Israpundit and Soccer Dad.