when you asked this question I figured I'd send an email to Spider Robinson and ask - his response:
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your memory works better than mine. It took me awhile to dig out the memory of what was the second Callahan's Place story I ever sold. Since it had been over a year since my first sale, and I'd collected 14 rejection slips since, it's a happy memory, which always helps.
Yes, the story you remember was "The Time Traveler," if I'm remembering right. But the controversy part is just a bit of an exaggeration. I wish I could check my memory against Ben Bova's excellent one, but my recollection is, what actually happened was he got one or two letters complaining that that story was not science fiction. Ben wrote back to both that first of all, he felt it was, that science fiction did not necessarily have to contain machinery of any kind—just change—and concluded by saying, come on, you've got a complaint about one story out of the hundreds you've read here, and you threaten to cancel your subscription? You have that right, and I'm sorry you feel that way; have a nice day.
Then he told me privately that he'd checked, and nobody had canceled their subscription. But it made a great story, so we both retold it over the years.
I've said it before, and I'll say it again. As Dizzy Gillespie said about Charlie Parker, no Ben, no me. In his last years, he used to tell me he was starting to feel like one of the last legionnaires still defending Fort Zindeneuf, and now it's my turn.
Thanks for reminding me what an uncannily lucky sumbitch I am and have been.
—Spider
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at the bottom he had the following inspirational quote
We like believing the best
because nothing needs to be done about it,
and the worst, because nothing can.
—James Richardson