Jhp is the only one that moves her forward, therefore, it's the only move that would benefit from projectile soak, none of the other moves would matter as you gain no ground
That was kind of the point. If you don't give installed j.Hp projectile invulnerability, then all of the invulnerable moves are close range and non-mobile. So basically H.lasering in range of those attacks would lose every time. You would either have to jump, block or use a non-projectile move that hits five times like Hp, which sounds reasonable to me given that it takes 2 meter.
Last I checked, Painwheel has 4 Heavy Hatred Attacks, with the 4th you forgot about being c.HP. That hits overhead and causes ground bounce. Second, Painwheel has 9 armored normals. Her s.LP, s.MP, s.MK, c.LP & c.MP being the other five you're not mentioning. Additionally, Buer Overdrive has armor. If we're giving her heavies access to projectile armor then I have to ask if this also gets it. If you give that thing projectile invulnerability it is going to beat every single projectile super in the game.
Oh yeah I forgot about c.Hp. And I deliberatively left out the lights and mediums because adding projectile invulnerability to every charged move seems broken at worst and pointless at best. The original idea was that it would only apply to charged heavies, since those have delayed startup and give you enough time to react, either by jumping, blocking or using a fast multi hit attack. In regards to beating supers, yeah that would be bad, which is why I suggested only making it on Robo.
Let me narrow it down to something that is potentially reasonable: Robo's lasers no longer stop Painwheel's charged heavy landed installed normals. Most of the time PW's heavies go through the lasers anyway, this would just stop the few times when the timing was perfect and they hit enough times to stop it. The idea would be to help PW players stay in once they get past her zoning, and encourage Robo players not to just through out a lasers when she has better options up close.
If I remember right, in the patch notes stream when Mike was explaining the change he said "Lasers no longer stop three hit armor moves." Maybe I'm misremembering, maybe he misspoke or maybe it was implied that it only applies to BB's H. A-Train since that what he was showing. However, if he did mean it generally as a means of nerfing Robo, then all of PW's charged landed heavies (even uninstalled) and her installed j.Hp would go through it, since they all have three hits of armor (correct me if I'm wrong on that). I know that the j.Hp going through lasers would make the match-up horribly skewed in PW favor, but it is only for the duration of the install and does cost 2 meter to do.
I just figured that since this kind of change was considered for BB but then changed because of reasons, I would suggest considering it for PW, since a the two main concerns I saw concerning A-Train (high mobility and sliding knockdown) don't apply to Painwheel's moves. Even the increased hitstop when the laser hits SSJ could work to prevent j.Hp from approaching to much. I feel like the PW vs Robo match-up is pretty even right now, and considering that Robo is basically getting all around buffs, this would help PW to get and stay in without having to rely on flying above the laser's range.