Best he could come up with off the top of his head. By now we all know that he will say anything that advances his agenda, but couldn't he at least come up with some lies that are harder to disprove? He does have some smart people working for him I imagine. He should at least make good use of them.
He might have been honestly wrong rather than fabricating. I doubt he has the pay rates of Capitol staff at his fingertips. Probably he heard that some janitors somewhere in federal service were going to get a pay cut, and erroneously extrapolated to Capitol janitors.
"Never assume conspiracy when cock-up will adequately explain the facts". Republican paranoia about Obama simultaneously implies great malice and omnipotent ability. Neither are correct.