I was imagining more like an early game rush where you start building it in their system within the first few minutes of the game, but maybe this just won't work?

Oldschool SB rush took some skill. This mobilization crap doesn't require anything. Ourterra can do it.

This might be a dumb question, but why don't they just kill you while you're building your 8 research labs?

It's mainly eco players who manage to do this...if you are protected on each flank by an ally, it is virtually impossible for someone to prevent you from getting the labs and the planets to support such an endeavor...

Even unskilled players can do it really easily if they have good frontliners...nothing more aggravating than surviving suicide spot only to have both flanks hit by moving SBs (and other shit) while you're dealing with cleaning up 2 players....

Yeah I pulled it off more than once sometimes against skilled player. 

While you can plant sb accompanies with skirantra with repair cloud and fleet that you are building and build it up from scratch in 3-5 min the mobilization rush is different.

You do need fleet for that I usually plant sb at choke point and have small fleet to defend if he tries to bypass. Problem with bypassing is that his ships once leaving grav well with SB will take damage and he wont be able to bring reinforcements and usually player that is defending has advantage due to having his factories closer and he can respond and can build counters and/fleet faster. Then It is just a matter of getting 8 labs + resources for research which is not such a big investment.

Usually guy who I was fighting spend his resources to try to develop fleet or eco up. If he doesn't get ogrows in enough numbers very soon because of corvettes you can spam his attempt is futile....

PS as vasari it is very easy to defend against SB rush. SB combined with turret that has anti passive regeneration on it will do the trick ....