Can you really tender and sign a player and then remove him from the 40-man roster before the Rule V,? I see what you mean about the salary scaring off claimants (on regular waivers I'd think, Rule V wouldn't be an issue after that) though.
Agreed it's not a lot of money but if it's about the 40-man space a prospect is probably more valuable than a marginal guy who also makes $6 million (he last made $4.5). And even though the Phillies are made of money, guaranteeing a marginal player that much really isn't good business. There's that loophole where you cut him at a certain point in ST but I'd still rather take my dumpster-dives at dumpster prices.
He would have to be a serious candidate for the rotation to stick around on anything other than minor league deal, IMO. If you're paying him $6 million he's almost guaranteed to be the 5th starter, at least initially, and at the expense of adding a second veteran. In other words, he'd be your new Clay Bucholtz. Which might be okay, if he fizzles he gets replaced internally, if he thrives, he gets traded. But I know that's not the level of talent people are hoping for from that second rotation upgrade (to say nothing of the first).