Yup. They absolutely refuse to give us an official answer/choice.
Like someone else mentioned, it's odd that in GTA V it's called "Roman's Taxi Service" whereas it was named something more ambiguous in GTA IV. It's most likely referenced as "Roman's Taxi Service" to make the easter egg more noticeable. Not everyone would easily be able to pick out the real name and say: "Woah sh*t! That's the cab company from GTA IV!"
Then there's Niko having a Life Invader page, though in GTA IV he's a bit of a "technophobe" as described by Roman.
In GTA V you have easter eggs that may or may not be canon, suggesting that Roman may or may not be alive.
In GTA IV, you have Packie talking about how he has to stay in LC if something ever happened to Kate, because no one else can take care of Ma. Yet in TBoGT, we can see Packie leaving Liberty City and boarding a plane - most likely to Los Santos. It's worth mentioning TBoGT's final mission/credit scenes take place the day after IV's ending.
If Kate is dead, than Packie could not leave for LS at the end of TBoGT. This cancels the possibility of the Revenge ending being able to happen.
Yet here we are in GTA V, where there are easter eggs that may or may not be canon, saying Roman might be alive.
Rockstar obviously likes to tease us with hints and clues that either ending might be possible. They're never going to confirm it.
Personally, I like to look at the trailers for answers, and the Deal ending and Ending C are the only endings that have scenes and dialogue that show up in the game's trailers. Along with a few other reasons that I take into consideration when it comes to the "canon" choices in IV, and the "canon" heists in GTA V. But that's a whole different thing I don't want to get into.