I've played this card for a bit and wanted to share some observations. It's one of the more generically strong Anarch cards of the Red Sand cycle; it's just a good card and doesn't require a special self-damage or tag-me archetype. It's the new mini Vamp and much more fair in design.
What's Mining Accident good at? The bad pub from it makes running super efficient. In particular, the conspiracy breakers (Paperclip, Black Orchestra, MKUltra) are a solid breaker suite which benefit from bad pub. Bad pub contributes to install costs as well as break costs. Also, Blorchestra and MK have very high minimum expenditures; even the cheapest code gates and sentries cost 3. Cutting that down to 2 or 1 real s pays off quickly when making repeated runs.
MA is good early because a central is typically open and the corp cannot afford to lose 5; it opens them up to too many vulnerabilities (Medium, Account Siphon, etc.) & pushes them further away from IPO's play cost. Basically, being set behind your whole opening credit pool is cannot be endured on turn 2 or 3.
People will lean towards playing MA in Valencia because the words "bad publicity" appear on the Valencia ID. I don't think the card needs to stay there but the nice thing about Val is you expect to already have bad pub. Val is great for run-based tactics so cards like Dirty Laundry, Desperado, and Street Peddler (because you can install during a run) are a natural fit. Finally, without Blackmail, I don't see any corp bothering to play bad pub removal. It's just not worth the tech slots & there are far worse things to worry about.
When's MA bad? When the corp is rich & can just lose 5 without much harm, when it's late in the game & giving a bad pub isn't consequential, when all central servers are ICEd up & meeting its condition becomes expensive. It's bad quite often, which is why it's a balanced card.
I think the cheese bad pub spam strategies featuring Itinerant Protesters are going to be bad, interesting jank but not competitive. For one, Alice, Hacktivist, & Maw already attack corp hand sizemore effectively. Hack & Maw in particular are random discards which makes them quite valuable post-Jackson. For two, as I've learned playing against those cards, the correct move as corp is often to just empty your hand of useful cards & play in topdeck mode. It's not great but it's also not so bad that building a runner strategy around it is worthwhile.