Yes I think I wrote:
I'm still saying yes very quickly.
A 2:30 marathoner who has some muscle might actually be better even faster.
At what level? If you are talking about entry level racing then yes, on the start line of a cat 5 bike race, that guy would likely be in the top 3 or better in terms of fitness. Similar for cat 4. We've seen this with Sage, he has hopped on his bike and done some all out hills a couple years ago. His time were nowhere near the elite cyclists, but were still quite good, I'd say respectable Cat1/2 level. So right in the middle of the top amateurs (just under 30' on Flagstaff, mid to high 5' on NCAR, or about 4.5 w/kg for 30' and 5.2-5.5 or so w/kg for 5').
Sage might have an initial starting advantage though with his mountain running being advantageous for quad muscle development.
That said, if Sage showed up on the startline of a Cat4/5 bike race, that wasn't a pure hillclimb, he would get murdered. In the wrong race, he would flat out be in the wrong spot at the wrong time, miss a key split, and be dropped. In a calmer race he'd finish midpack without ever being in contention. Bike racing has all kinds of tactics and skills you need to have to be effective. You have to know when to jump on the gas, when to ease off, how to corner with the bunch, when are the times to put pressure on or ease off, how to surf wheels efficiently, when to move up, etc. Sage would have better fitness than most of the 4/5 guys, but he'd wouldn't be efficient on his bike and would waste a ton of energy being in the wrong places at the wrong times.
If Sage was in a Cat2 race, likely his current fitness level, he'd be promptly dropped. The lack of race skills would be too much in that race, as would the duration and especially the repetition of the really hard effort over and over again. Most guys in Cat2 can probably rip out 6w/kg or close for 5'...not many can do it 4-10 times over the course of a 3 hour bike race and then deliver a strong sprint or uphill kick. That's also what you saw with Woods. He had great one off climbs or intervals almost from the start...but still was not an immediate factor at domestic pro levels. Why? His tactics/race skills/positioning sucked, and he didn't have staying power to repeat and repeat these hard effort.
The question doesn't seem to imply that, but if the question is if a 2:10 guy had a year or two could he be an effective bike racer...the answer is yes. If focused, I would suspect well over 95% of 2:10 guys could become respectable Cat1 racers, or better, given 2-3 years to develop bike racing skills.