Were the tribes of Gad, Manasseh, and Reuben Out of God's Will?

In the past few years, I have sometimes heard (or read on social media) that the Israelite tribes of Reuben, Gad, and the half-tribe of Manasseh were disobedient to God's command and will for them when they took as their possession the lands of kings whom Israel conquered on the east side of the Jordan River, rather than settling in Canaan with the rest of the tribes. Well-meaning people have tried to use these three Transjordan tribes as examples of people who didn't "press into all God had for them," and instead settled for a lesser relationship/blessing.

Most people seem to get the idea that these tribes were less than fully obedient from Moses' reaction to them when they requested that he give them that territory as their inheritance in Numbers 32:6-9:

Moses said to the Gadites and Reubenites, “Should your fellow Israelites go to war while you sit here? Why do you discourage the Israelites from crossing over into the land the Lord has given them? This is what your fathers did when I sent them from Kadesh Barnea to look over the land. After they went up to the Valley of Eshkol and viewed the land, they discouraged the Israelites from entering the land the Lord had given them.

And then in verses 14-15, Moses directly accuses them of sinning by making this request:

“And here you are, a brood of sinners, standing in the place of your fathers and making the Lord even more angry with Israel. If you turn away from following him, he will again leave all this people in the wilderness, and you will be the cause of their destruction.”

The leaders of these three tribes then respond to Moses, saying that the fighting men among them will accompany their fellow Israelites into Canaan to help them conquer the land, and will return to their wives and children living in the fortified cities east of the Jordan only after the rest of Israel has taken possession of their own inheritance. 

Moses then replies in vv. 20-24:

“If you will do this—if you will arm yourselves before the Lord for battle and if all of you who are armed cross over the Jordan before the Lord until he has driven his enemies out before him—then when the land is subdued before the Lord, you may return and be free from your obligation to the Lord and to Israel. And this land will be your possession before the Lord. But if you fail to do this, you will be sinning against the Lord; and you may be sure that your sin will find you out. Build cities for your women and children, and pens for your flocks, but do what you have promised.”

So, Moses seems to change his mind about the tribes' request, landing at the position that as long as they keep their promise to help the other tribes possess the Promised Land, then their own settling east of the Jordan would not be sinful disobedience. Note that nowhere in this passage does it say that Moses consulted God about this matter. He seems rather to be initially reacting based on his prior experience of the previous generation being unwilling to take the land due to their fear of the land's inhabitants. 

If we move on to the next book in the Pentateuch, when Moses is recounting to Israel all that the Lord has done for them and renewing the covenant with the new generation before they enter Canaan, we find that Deuteronomy 2:24 says:

“Set out now and cross the Arnon Gorge. See, I have given into your hand Sihon the Amorite, king of Heshbon, and his country. Begin to take possession of it and engage him in battle.”

And verse 31 says:

The Lord said to me, “See, I have begun to deliver Sihon and his country over to you. Now begin to conquer and possess his land.”

Here in Deuteronomy, when Moses is recounting the Israelites' history, he seems to acknowledge that the lands east of the Jordan were give by God to Israel as a possession, just as the promised territory of Canaan was going to be given into their hands. 

Please understand that the point of this post is not to say that we shouldn't press into all that God has for us. I'm just saying that we should be careful in our handling of the biblical text, and not make a practice of making an otherwise valid point from a passage that isn't really presenting that point.