So because of a perception of “no level of intellectual level from the ‘religionists’” (is that an epithet?), that excuses the lack of “intellectual rigor from those who wear the mantle of rationality and adherence to science”. Since when does a race to debasement by both “sides” of an argument (so presumed) achieve, or rather signify, anything?
But let's not pretend that our friend is being a self proclaimed equal opportunity mediator.
I laid out a short version of non-supernatural morality earlier. I've asked for a similar definition from the theistic side and haven't gotten one.
If I had to guess, it's because he knows that he'll open up an intellectual can of worms by saying "My morality comes from the Bible", as those of us who don't agree with you and he easily go line by line documenting the death, destruction, and misery commanded by the "transcendent authority" in the OT.
The best defense is a good offense. I can't fault him for not putting his convictions on the line, as they are likely indefensible.