The question of whether "portable Starlink" (the aviation/maritime++ category we're talking about) justifies Starship's existence is whether the marginal increase in payload capacity or efficiency of Starship over Falcon produces a marginal increase in "portable Starlink" profit that's multiples beyond the amortized development cost and the launch costs of Starship.
Given that Starlink's entire enterprise is probably loss-making if it had to pay for its own launch capacity (it currently pays SpaceX Space $0 and is accounted for just in hardware depreciation, so frontloads profit and all the costs are incurred in coming years)... the answer is almost certainly no.
And for what it's worth, the one aircraft I've been on with Starlink Internet was (by a gigantic margin) the worst in-flight wifi experience I've had in 10 years. I'm curious how much of cost-savings it is over the current alternatives. I hope it's a lot because there's a long road between here and whenever I'd willingly buy a seat on a Starlink-connected flight again.