I suspect he thinks it will be easier to write a language parser that follows one basic syntactical idiom.I doubt that for two reasons.
First, Bryce has been vocal in his opposition to any language feature that is done for the purpose of making parsing easier.
Second, I have my doubts about whether Bryce ever intends to write a parser, so I wouldn't think he's too concerned with parsing issues.
I guess while we're on the subject, I might as well ask how the syntax lays out when the number of parameters is not 2. What does the syntax do when there is only a single parameter? What does the syntax do when there are three or more parameters?
Haskell gets away with it by stipulating that all functions take only a single parameter. Additional parameters are Curried in functions that also take a single argument.
Python, OTOH, always takes a single parameter, but the parameter may be a tuple which allows multiple parameter to be group together as a single parameter.