Actually, it would be significantly LESS scriptural to do so. If you take a look at St. Paul's letters, you will see continuing prayers for the Jews. For example:
Rom 9:30-10:4 -- What shall we say, then? That Gentiles who did not pursue righteousness have attained it, that is, righteousness through faith; but that Israel who pursued the righteousness which is based on law did not succeed in fulfilling that law. Why? Because they did not pursue it through faith, but as if it were based on works. They have stumbled over the stumbling stone, as it is written, "Behold, I am laying in Zion a stone that will make men stumble, a rock that will make them fall; and he who believes in him will not be put to shame."Brethren, my heart's desire and prayer to God for them is that they may be saved. I bear them witness that they have a zeal for God, but it is not enlightened. For, being ignorant of the righteousness that comes from God, and seeking to establish their own, they did not submit to God's righteousness. For Christ is the end of the law, that every one who has faith may be justified.
As for prayers for the Mohammedans, they already exist: these are prayers for the pagans (of which, the Mohammedans are a subset).
The liturgy is not something to be changed helter-skelter.