So he didn't respect Marco, Vista, and the other veteran members? Whitebeard was calling them son even at Marineford. You're also exaggerating the age gap between Oden and WB. They were 7 years apart. He was nowhere near the age to claim to be Oden's father.
Rocks had no one in his crew that was leading that era with him or portrayed equally to him. If you want a better use of this comparison, it'd be like if Garp or Roger joined Rocks.
Along with Oden never being shown on the level of WB and Roger, Yamato is the next Oden. That really shouldn't be a debate at this point.
Law and Oden have more in common than Yamato and Oden and I believe Oda knows this and drops small hints. Again I want to make it clear, whether he "officially" joins or not is irrelevant. I believe Law will continue to sail with the Straw Hats just because the story dictates it, and Oda is dropping hints that he will be similar to Oden as he was never considered a full member of the Roger pirates