As it should be; a weaker member is like a failed raid drive rebuilding until it's up to speed with the team. You expect things to go slower until he's up to speed. If speed is necessary, the senior programmer can always drive and let the other guy watch and ask questions, or explain as he goes along.

But, in this case, the weaker member was the senior--seniority in the company, anyway--and kept the stronger member from getting anything done.