Mister House: Mr. House would have no interest in these brainwashed spear chucking savages. Unless they could be brainwashed by him to act as a personal army. but most are probably to devoted to Ceaser or fear Legate and have learned to hate House. So nooooo. Also NCR and Remnant fighting? Yeaaaah. Remnant has manpower to an even lesser extent than the BOS and most need hip replacements. So No.

NCR: I am tired of all this BOS and Enclave [censored]. CL would have devoured these small groups.

Caesar's Legion: Only reason Legate would want you after Graham would be to kill him or his rumors

Yes Man: Yesman: Courier I need you to expand territory and increase sovereign control over the Mojave wasteland!
Courier: How bout no?
Yes Man: OKEY DOKEY! You'll never hear about these plans again!