There might be a glitch in cross-communication, since NFO isn't being very clear about what he's talking about. As a random example, since we're talking ICBMs, the LGM-118 Peacekeepers, were designed to carry up to 10 reentry vehicles, each of which could carry a minimum of 300kt-yield warhead (the W87s, which could theoretically be upscaled to 475kt according to the known design specs), but this program was ended and the Peacekeepers decommissioned. The mainstay of the American ICBM strategic arsenal, the Minuteman-III, is to be rigged to carry a single one of these same warheads, or three of the older W78s it was originally designed for; the W78s have a yield of 335-350kt each. The Russian R-36 variants are theoretically capable of throwing 50 warheads onto a single missile, but has to common knowledge never been rigged for more than 10 with the remaining 40 dedicated to pen-aids; each of its warheads was 500 kt or 800kt. It is also capable of launching a single warhead payload of 20 MT. This is very likely what NFO is referring to when he refers to ICBM strikes in megaton range. While each individual warhead is nowhere near the scale of the Tsar Bomba, a standard R-36 with a MIRV payload could put out an aggregate strike equivalent to the megatonne range, and a R-36M2 would be a fearsome vision in the milliseconds before it burns your retinas out. This is a single weapon, but it is very much not a single warhead.
NFO, though, you should actually try to back up your statements on your own. Simply blankly repeating the original assertion over and over again does not help your case when the assertion is precisely what is being questioned, nor does it the use of bold or understrokes facilitate reasonable communication. The fact that "you cannot compare a bomber-delivered weapon to an ICBM delivered weapon" (which is false; it's done all the time, albeit in more general ways) has no bearing on the theoretical capabilities you ascribe to any single strategic nuclear weapon (which, by the way, is a category that does include bomber-delivered weapons, most notably the B83 which can be used for both roles). That said, I would love to see which weapon you're referring to that you claim has a maximum throw of 50-250 MT. The closest I'm seeing is the R-36M2 with the pen-aids replaced by 40 more warheads, which seems to cracks a theoretical equivalent 25 MT assuming no overlap (and by this I mean that I'm talking out of my chair, so to speak), but more practically would likely just replace the lot with a single 20MT in any actual use-case scenario if that kind of weight is required. The aformentioned Titan is the largest American model, and its TNT-equivalent has already been given by SquatchHammer; the Titan-2 seems to be over twice that, but 9MT still doesn't match up to 50.