Michael Piller would after that season was over, in Cinemafantastique say that the "2,000 Romulans" were supposed to be a "Trojan Horse" type of an attack.
By this I assume he meant that the Romulans would've seized key parts of Vulcan planetary defenses and allowed a much larger force in.
Piller basically stated that it was impossible budgetwise to stage a "real invasion" of Vulcan and it made no sense for a handful of stolen ships to carry a real invasion force.