Twiggs was taken at the point of a gun to negotiate with the Texas Commissioners. (His capture is reenacted every year, I think.)
He wasn't in a strong negotiating position. Texas troops far outnumbered and surrounded the US force and the War Department had not given him any guidance on what to do if this happened despite his asking (more than once I think). To resist would have begun the WBTS. Sam Houston helped convince Twiggs not to start the war in Texas, IIRC.
Apparently, there was shouting back and forth in the negotiations with the captured Twiggs, but Twiggs managed to get the OK for his troops, some supplies, and their arms (small arms, at least) to go to the coast where they would be shipped north. The transfer of US troops to the north was interrupted after Sumter fell. Those federal troops that were still in Texas at that time became some of the first prisoners of war.
And the managed to kiss and make up in time for Twiggs to become a confederate general? Come on.