Would Saruman have been a reliable ally?

[Inziladun]

Originally Posted by Tuor in Gondolin

It is interesting to speculate what kind of "great sevice" Saruman
could have rendered. Perhaps helping to protect eastern Rohan so as
to release more forces for the ride to Minas Tirith, say 8,000 vs.
the 6,000 brought.

Since Saruman knew so much of not only the Ring, but also of Sauron (through study of his works and mental communion via the Palantíri), I think he would have been of much help in devising military tactics for the West that would have been likely to divert his attention from Frodo and Sam.

[Faramir Jones]

Originally Posted by Inziladun

Since Saruman knew so much of not only the Ring, but also of Sauron (through study of his works and mental communion via the Palantíri), I think he would have been of much help in devising military tactics for the West that would have been likely to divert his attention from Frodo and Sam.

I agree that Saruman would be a powerful ally; but as has been pointed out, he would not be trusted by most by the time of the parley at Orthanc. Certainly the Rohirrim were angry at his attempts to subvert their king and his family, not to mention the loss of life and property. Why should they, to give an example, trust Saruman?

There's also the attitude of the Gondorians. Isengard was still Gondorian when Ruling Steward Beren gave him the keys of Orthanc. Later, Saruman declared his independence, renouncing any obligations towards Gondor. I don't see any of the Stewards, much less Denethor II, believing in any professed repentance, not just because of what he did to Gondor, but also, as I mentioned, what he did to Gondor's close ally Rohan.