Just so everyone is clear, we all agree that this is just food for thought? I have witnessed people arguing and getting angry at the disagreement of this topic many times and it's not worth fighting about. I do not believe that it's the biggest deal in the world right now especially concerning salvation. I was not part of the church discussion so I don't know if that was said there but I felt like I should add that disclaimer.
That being said, I personally have not necessarily chosen a side as to which I believe Genesis 6 is referring to. There are strong arguments for both sides.
Something else to take into consideration, angels through out the bible have appeared unto men as if they have a fleshly body,
Genesis 19:1 And there came two angels to Sodom at even; and Lot sat in the gate of Sodom: and Lot seeing them rose up to meet them; and he bowed himself with his face toward the ground;
Genesis 19:5 And they called unto Lot, and said unto him, Where are the men which came in to thee this night? bring them out unto us, that we may know them.
Genesis 19:8 Behold now, I have two daughters which have not known man; let me, I pray you, bring them out unto you, and do ye to them as is good in your eyes: only unto these men do nothing; for therefore came they under the shadow of my roof.
Genesis 19:12 And the men said unto Lot, Hast thou here any besides? son in law, and thy sons, and thy daughters, and whatsoever thou hast in the city, bring them out of this place:
Genesis 19:15 And when the morning arose, then the angels hastened Lot, saying, Arise, take thy wife, and thy two daughters, which are here; lest thou be consumed in the iniquity of the city.
The angels are referred to as angels and men interchangeably, probably because they took the form of men at the time.
I would be willing to be corrected through scripture on this as well, but it seems as though angels have free will. How else could lucifer be lifted in his own pride and fall?
Daniel 10:5-6 Then I lifted up mine eyes, and looked, and behold a certain man clothed in linen, whose loins were girded with fine gold of Uphaz: His body also was like the beryl, and his face as the appearance of lightning, and his eyes as lamps of fire, and his arms and his feet like in colour to polished brass, and the voice of his words like the voice of a multitude.
I know all that sounds like I'm leaning toward Gen 6 referring to angels, but I'm not so sure, in matthew 22, doesn't Jesus teach that the angels neither marry nor are given in marriage?
Matthew 22:23-30 The same day came to him the Sadducees, which say that there is no resurrection, and asked him, Saying, Master, Moses said, If a man die, having no children, his brother shall marry his wife, and raise up seed unto his brother.
Now there were with us seven brethren: and the first, when he had married a wife, deceased, and, having no issue, left his wife unto his brother: Likewise the second also, and the third, unto the seventh.
And last of all the woman died also. Therefore in the resurrection whose wife shall she be of the seven? for they all had her.
Jesus answered and said unto them, Ye do err, not knowing the scriptures, nor the power of God. For in the resurrection they neither marry, nor are given in marriage, but are as the angels of God in heaven.
Sounds to me like angels are not actually flesh but can appear as flesh if they choose. I know that is referring to in the resurrection and angels of God IN heaven but I think it's worth mentioning here.