A certain logical consistency would demand this response out of everyone who uses "one mediator" (1 Timothy 2:5) in such a way as to forbid intercession by people who aren't exactly Jesus (cf. 1 Timothy 2:1).
At least to my mind, a stronger objection would be the whole idea of "talking to dead people" or that requesting the prayers of those who have died does not enjoy the scriptural support that exists for requesting the prayers of those who are still living. (Yes, I'm aware of counter-arguments.) Even so, for some reason "one mediator!" seems to appear more often in my experience. And yet no one seems to use it to discourage (or interrupt) threads requesting prayer. If "one mediator" means what some people says, they should.
I see no difference, in terms of "one mediator," between asking the "living" for their prayers and asking the "dead" for their prayers. If asking the most famous Mary for prayers would betray some lack in trust in Jesus as the one mediator, then asking Mary Smith for prayers at the Wednesday evening prayer meeting would also betray some lack of trust in Jesus as the one mediator.
The same Paul who wrote "one mediator" prayed for others and asked others to pray for him in multiple letters (for example, Romans 15:30, Ephesians 6:19, Colossians 4:3, 1 Thessalonians 5:25, 2 Thessalonians 3:1). I see no indication that his position had changed between other writings and 1 Timothy (let alone between 1 Timothy 2:1 and 1 Timothy 2:5). Colossians 4:12 reads, "Epaphras, who is one of you, a servant of Christ, saluteth you, always labouring fervently for you in prayers, that ye may stand perfect and complete in all the will of God." It does not read "Epaphras, who is one of you, is always labouring fervently for you in prayers, but he is a fool because there is one mediator between God and men, the man Christ Jesus."
Christ Jesus seemingly would have us pray for others who "despitefully use" us (Matthew 5:44, Luke 6:28) and didn't forbid us from praying for them because "there is one mediator."
Not quite. Actually you've wandered a little off the path of logic.
Mary is dead; in Heaven no doubt, but NOT omniscient; asking you friend to pray for you is reasonable; that person, properly, would be praying to GOD on your behalf; not to Mary.
See the difference?
Hoss