I don’t see any valid argument anywhere that would preclude Biden from assuming the presidency.
I don't either, and that's where the author fails in his reasoning. Some have suggested that the entire election would be negated, and perhaps McCain/Palin would assume office. That's wishful thinking. Obama's ineligibility would mean that Biden succeeds him based on Constitutional succession. I simply can't see the courts ruling otherwise.
As for his time in office, and the laws passed, that's where the turmoil will develop. And you can be assured the libs will fight to have them retained, tooth and nail.
Only if the Supreme Court held that the election was void because of Obama's ineligibility. In that case, Biden would not be legally the VP. In the meantime Pelosi would take over while the Senate and House would have to go over the election results and figure out how to certify a winner. McCain's and Palin's electors should stand, but who knows how the Dems will do with the others.
How can the election be valid if the person running for president was invalid? If nothing else...McCain would be president and Biden Vice President, maybe?