"方便倒是方便" seems like a fixed expression, and from context it seems to be rejecting "is it convenient?" as a reason for doing something. I can't find an actual definition, though.
方便倒是方便 roughly means though it's convenient. Usually it goes like 方便倒是方便, 可是 ... ... It implies there could be some other negative factors or concerns (though it's convenient).
E.g. (quote from online):
Without getting too wordy in translation:
Could you pick up my parcel for me?
Yes, but right now I have something else to do.
方便倒是方便 here = yes