All this can be refuted by the simple "it's a rebuy" argument.
We've accumulated chips? It's a rebuy, we only have three times our starting stack (assuming we rebought immediately), and three times our starting stack is not enough to sit back on.
Why should we not wait for a 'top' hand? It's a rebuy - villain may get bored, lose a few more hands and quit shortly, we might get moved around tables, villain could go on a heater, multiply his stack by 10 and quit shoving every hand, we might not get any huge hands we can call with. Basically, the list of variables is large, and due to the very nature of rebuys we should be looking to accumulate chips wherever possible, whether it be with 55% equity or with 80% equity.
We're not 'coinflipping' either. A range of 77+/AK-A8/KQ-KJ has ~66% equity against a range of any two cards. Obviously we need to be aware of the possibility of SB or BB having a huge hand and calling, but this is unlikely and so doesn't affect things too much.
Finally, umm, how is it possible to get a better read on anyone than the "Is shoving any two cards preflop" read we have on villain at the moment?